# Conceptual Physics: Questions On Rotational Motion

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• 1.

### Horses that move with the fastest linear speed on a merry-go-round are located

• A.

Near the center

• B.

Near the outside

• C.

Anywhere, because they all move at the same speed

B. Near the outside
Explanation
Horses that are located near the outside of a merry-go-round move with the fastest linear speed because they have to cover a greater distance in the same amount of time compared to horses located near the center. As the merry-go-round rotates, the horses on the outside have to travel a larger circumference, resulting in a higher linear speed. On the other hand, horses near the center have a smaller circumference to cover, so their linear speed is slower. Therefore, the horses near the outside of the merry-go-round move with the fastest linear speed.

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• 2.

### Your pet hamster sits on a record player whose angular speed is constant. If he moves to a point twice as far from the center, then his linear speed

• A.

Doubles

• B.

Halves

• C.

Remains the same

A. Doubles
Explanation
When the hamster moves to a point that is twice as far from the center of the record player, its linear speed will double. This is because linear speed is directly proportional to the distance from the center of rotation. As the hamster moves to a point twice as far from the center, the distance it covers in a given time also doubles, resulting in a doubling of its linear speed.

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• 3.

### Since each rolling wheel of a railroad train is tapered, the narrow part of the wheel has a tangential speed that is

• A.

Greater than that of the wide part

• B.

Smaller than that of the wide part

• C.

The same as that of the wide part

B. Smaller than that of the wide part
Explanation
The correct answer is "smaller than that of the wide part". This is because the tapered shape of the wheel causes the circumference to decrease towards the narrow part. As a result, the distance covered by the narrow part in one rotation is smaller than that covered by the wide part. Since the speed is defined as the distance covered per unit time, the narrow part of the wheel will have a smaller tangential speed compared to the wide part.

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• 4.

### When a train makes a curve, different parts of the wheel rims

• A.

Cover a different distance in the same time

• B.

Must all expand at the same time

• C.

Must all contract at the same time

• D.

Vibrate at different rates

A. Cover a different distance in the same time
Explanation
When a train makes a curve, different parts of the wheel rims cover a different distance in the same time because the outer part of the wheel has to travel a larger circumference compared to the inner part. As a result, the outer part of the wheel covers a greater distance in the same time as the inner part. This difference in distance covered is necessary to ensure that the train can smoothly navigate the curve without derailing.

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• 5.

### The tapered shape of the parts of the wheels that ride on railroad tracks allows opposite wheels to

• A.

In effect, vary their diameters

• B.

Travel at different linear speeds for the same rotational speed

• C.

Both A and B are correct

C. Both A and B are correct
Explanation
The tapered shape of the parts of the wheels that ride on railroad tracks allows opposite wheels to vary their diameters. This is because the tapered shape causes the wheels to have different radii at different points, allowing them to effectively change their diameters. As a result, when the wheels rotate at the same speed, they will travel at different linear speeds. Therefore, both statement A and B are correct.

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• 6.

### Which moves faster in m/s on a merry-go-round: a horse on the inside or a horse on the outside near the outer rail?

• A.

Inside horse

• B.

Outside horse

• C.

Both move at the same speed in m/s

B. Outside horse
Explanation
The outside horse moves faster in m/s on a merry-go-round compared to the inside horse. This is because the outside horse has to travel a larger circumference than the inside horse in the same amount of time. Since speed is defined as distance traveled per unit of time, the outside horse covers a greater distance in the same time period, resulting in a higher speed.

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• 7.

### If a turntable's rotational speed is doubled, then the linear speed of a pet hamster sitting on the edge of the record will

• A.

Double

• B.

Double

• C.

Remain the same

A. Double
Explanation
When a turntable's rotational speed is doubled, it means that it is rotating at a faster rate. Since the pet hamster is sitting on the edge of the record, which is attached to the turntable, it will also experience this increase in rotational speed. This increase in rotational speed directly translates to an increase in linear speed for the hamster. Therefore, the linear speed of the hamster will double.

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• 8.

### Suppose the circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per second when you are riding the bicycle, then your speed will be

• A.

1 m/s

• B.

2 m/s

• C.

3 m/s

• D.

3.14 m/s

• E.

6.28 m/s

B. 2 m/s
Explanation
The circumference of the bicycle wheel is 2 meters. When the wheel rotates at 1 revolution per second, it means that the wheel covers a distance equal to its circumference in 1 second. Therefore, the speed of the bicycle will be equal to the circumference of the wheel, which is 2 meters, per second. Hence, the correct answer is 2 m/s.

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• 9.

### Consider a string with several rocks tied along its length at equally spaced intervals. You whirl the string overhead so that the rocks follow circular paths. Compared to a rock in the middle of the string, a rock at the outer end moves

• A.

Half as fast

• B.

Twice as fast

• C.

At the same linear speed

B. Twice as fast
Explanation
A rock at the outer end of the string moves twice as fast compared to a rock in the middle of the string because it has a larger circumference to cover in the same amount of time. As the string is whirled overhead, the outer rock has to travel a longer distance in the same period of time, resulting in a higher speed.

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• 10.

### A broom is easier to balance on its end when the heavier end (the brush end) is

• A.

• B.

• C.

Same either way

B. Highest, farthest from your hand
Explanation
When balancing a broom on its end, the center of mass needs to be directly above the base to maintain stability. The brush end of the broom is heavier, so placing it higher and farther from your hand shifts the center of mass towards that end. This creates a more stable balance as the weight is distributed further away from your hand, allowing the broom to stay upright more easily.

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• 11.

### An industrial flywheel has a greater rotational inertia when most of its mass is

• A.

Nearest the rim

• B.

Nearest the axis

• C.

Uniformly spread out as in a disk

A. Nearest the rim
Explanation
When most of the mass of an industrial flywheel is located nearest the rim, it increases the flywheel's rotational inertia. Rotational inertia, also known as moment of inertia, is a measure of an object's resistance to changes in its rotational motion. By placing the mass near the rim, the flywheel's rotational inertia is increased because the mass is located farther away from the axis of rotation. This increases the object's resistance to changes in its rotational speed, making it harder to accelerate or decelerate.

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• 12.

### A coin and a ring roll down an incline starting at the same time. The one to reach the bottom first will be the

• A.

Ring

• B.

Coin

• C.

Both reach the bottom at the same time

B. Coin
Explanation
The coin will reach the bottom first because it has a smaller mass compared to the ring. As they both roll down the incline, the coin will experience less resistance and therefore accelerate faster. This means that the coin will cover the distance to the bottom in a shorter amount of time compared to the ring.

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• 13.

### The rotational inertia of your leg is greater when your leg is

• A.

Straight

• B.

Bent

• C.

Same either way

A. Straight
Explanation
When your leg is straight, it has a greater rotational inertia compared to when it is bent. Rotational inertia is a measure of an object's resistance to changes in its rotational motion. When your leg is straight, it has a longer moment arm, which is the distance between the axis of rotation and the mass of the object. This longer moment arm increases the rotational inertia of your leg, making it more difficult to rotate or change its rotational motion. On the other hand, when your leg is bent, the moment arm is shorter, resulting in a lower rotational inertia.

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• 14.

### A torque acting on an object tends to produce

• A.

Equilibrium

• B.

Rotation

• C.

Linear motion

• D.

Velocity

• E.

A center of gravity

B. Rotation
Explanation
When a torque acts on an object, it creates a rotational force that tends to make the object rotate around a fixed point or axis. This is why the correct answer is rotation. Torque is the product of force and the perpendicular distance from the axis of rotation, and it causes objects to rotate rather than move in a linear motion or change their center of gravity. Equilibrium refers to a state of balance, and velocity is the speed and direction of an object's motion, but neither directly relate to the effect of torque on an object.

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• 15.

### On a balanced seesaw, a boy three times as heavy as his partner sits

• A.

1/3 the distance from the fulcrum

• B.

Less than 1/3 the distance from the fulcrum

• C.

More than 1/3 the distance from the fulcrum

A. 1/3 the distance from the fulcrum
Explanation
The boy, being three times as heavy as his partner, needs to sit closer to the fulcrum in order to balance the seesaw. If he sat more than 1/3 the distance from the fulcrum, his weight would have a greater lever arm and the seesaw would be unbalanced. Therefore, he must sit 1/3 the distance from the fulcrum to maintain balance.

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• 16.

### Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively make the wrench handle twice as long, you'll multiply the torque by

• A.

Two

• B.

Four

• C.

Eight

A. Two
Explanation
By putting a pipe over the end of a wrench, the length of the wrench handle effectively doubles. This longer lever arm increases the torque applied to the nut. Since torque is directly proportional to the length of the lever arm, multiplying the length by two will also multiply the torque by two. Therefore, the correct answer is two.

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• 17.

### Toss a baseball bat into the air and it wobbles about its

• A.

Geometrical center

• B.

Center of mass

• C.

Heavier end

B. Center of mass
Explanation
When a baseball bat is tossed into the air, it wobbles about its center of mass. The center of mass is the point where the mass of an object is evenly distributed. In the case of the bat, the center of mass is the point where the bat would balance perfectly if it were placed on a fulcrum. As the bat rotates in the air, it wobbles around this point due to the uneven distribution of mass along its length. The heavier end of the bat does not necessarily determine the center of mass, as it depends on the distribution of mass along the entire length of the bat.

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• 18.

### The long, heavy tail of a spider monkey enables the monkey to easily vary its

• A.

Weight

• B.

Momentum

• C.

Inertia

• D.

Center of gravity

• E.

None of these

D. Center of gravity
Explanation
The long, heavy tail of a spider monkey enables the monkey to easily vary its center of gravity. The center of gravity is the point at which the weight of an object or organism is evenly distributed. By moving its tail, the spider monkey can shift its center of gravity, allowing it to maintain balance and stability while navigating through trees and swinging from branches. This adaptation is crucial for the monkey's arboreal lifestyle and helps it move efficiently in its environment.

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• 19.

### The center of mass of a human body is located at a point

• A.

That is fixed, but different for different people

• B.

That is always directly behind the belly button

• C.

That changes as a person bends over

• D.

None of these

C. That changes as a person bends over
Explanation
The center of mass of a human body is not fixed and changes as a person bends over. When a person bends over, their body's weight distribution shifts, causing the center of mass to move. This is because the position of the center of mass depends on the distribution of mass in the body. As the body bends, the distribution of mass changes, resulting in a shift in the location of the center of mass. Therefore, the correct answer is that the center of mass changes as a person bends over.

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• 20.

### The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is

• A.

Above a place of support.

• B.

Relatively low for such a tall building.

• C.

Stabilized by its structure.

• D.

Displaced from its center.

• E.

In the same place as its center of mass.

A. Above a place of support.
Explanation
The Leaning Tower of Pisa doesn't topple over because its center of gravity is above a place of support. This means that the weight of the tower is distributed in such a way that it creates a stable equilibrium. The tower leans due to a flaw in its construction, but the center of gravity remains above the base, preventing it from falling. As a result, the tower has managed to stand for centuries without collapsing.

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• 21.

### The chef at the infamous Fattening Tower of Pizza tosses a spinning disk of uncooked pizza dough into the air. The disk's diameter increases during the flight, while its rotational speed

• A.

Remains constant.

• B.

Increases.

• C.

Decreases.

C. Decreases.
Explanation
As the chef tosses the spinning disk of uncooked pizza dough into the air, the diameter of the disk increases. This means that the dough is spreading out and becoming thinner as it flies through the air. In order to conserve angular momentum, the rotational speed of the disk must decrease as the diameter increases. This is similar to how an ice skater spins slower when they extend their arms outwards. Therefore, the correct answer is that the rotational speed of the dough decreases.

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• 22.

### Centrifugal forces are an apparent reality to observers in a reference frame that is

• A.

Moving at constant velocity.

• B.

An inertial reference frame.

• C.

At rest.

• D.

Rotating.

• E.

None of these

D. Rotating.
Explanation
The statement "Centrifugal forces are an apparent reality to observers in a reference frame that is rotating" means that when an observer is in a reference frame that is rotating, they will perceive centrifugal forces. Centrifugal forces are the apparent outward forces experienced by objects in a rotating frame of reference, even though they are not actual forces. This is due to the inertia of the objects wanting to move in a straight line while the rotating frame of reference pulls them outward. Therefore, the correct answer is rotating.

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• 23.

### A person weighs less at the equator than at the poles. The main reason for this has to do with

• A.

The spin of the Earth.

• B.

The shape of the Earth.

• C.

The influence of the sun, moon, and all the planets.

• D.

The law of action and reaction.

A. The spin of the Earth.
Explanation
The correct answer is the spin of the Earth. As the Earth rotates, it bulges at the equator due to centrifugal force. This bulge causes a slight decrease in gravitational pull at the equator compared to the poles, resulting in a slightly lower weight for a person at the equator. The shape of the Earth and the influence of celestial bodies do have some impact on weight, but the main reason for the weight difference is the Earth's spin.

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• 24.

### When a twirling ice skater brings her arms inward, her rotational speed

• A.

Increases.

• B.

Decreases.

• C.

Remains the same.

A. Increases.
Explanation
When a twirling ice skater brings her arms inward, her rotational speed increases. This is due to the principle of conservation of angular momentum. As the skater brings her arms inward, her moment of inertia decreases, which causes her rotational speed to increase to maintain the same angular momentum. This can be understood by considering the analogy of an ice skater spinning on a chair. When the skater extends her arms, her rotational speed decreases, and when she brings her arms inward, her rotational speed increases.

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• 25.

### Consider a rotating donut-shaped space habitat where living quarters are on the inside surface farthest from the axis. If the rotational speed of the habitat increases, the apparent weight of people inside

• A.

Increases.

• B.

Decreases.

• C.

Stays the same.

• D.

Is always zero.

A. Increases.
Explanation
As the rotational speed of the donut-shaped space habitat increases, the centripetal force acting on the people inside also increases. This force is directed towards the axis of rotation and is responsible for the apparent weight that individuals experience. Therefore, with an increase in rotational speed, the apparent weight of people inside the habitat also increases.

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• 26.

### A baseball bat is balanced on a fulcrum. The center of gravity of the bat is located

• A.

Closer to the handgrip.

• B.

Above the fulcrum.

• C.

Near the heavy end.

B. Above the fulcrum.
Explanation
The center of gravity of a baseball bat is located above the fulcrum because the bat is heavier towards the end where the hitting surface is. This causes the center of gravity to be closer to the heavy end, resulting in it being positioned above the fulcrum.

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• 27.

### The center of gravity of a circular disk of sheet metal is

• A.

At the center of the disk.

• B.

Midway between the center and the outside.

• C.

Two-thirds of the way between the center and the outside.

• D.

Impossible to predict without knowing the metal density.

A. At the center of the disk.
Explanation
The center of gravity of a circular disk of sheet metal is at the center of the disk because the shape is symmetrical and the weight is evenly distributed around the center. Therefore, the gravitational forces acting on each part of the disk cancel each other out, resulting in the center of gravity being located at the center of the disk.

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• 28.

### If the Earth had two identical moons in one circular orbit, and the moons were as far apart in that orbit as they could be, the center of gravity of the Earth-moons system would be

• A.

At the center of the Earth.

• B.

Inside the Earth, but off center.

• C.

Outside the Earth, but within the orbital path of the moons.

• D.

Outside the Earth, but beyond the orbital path of the moons.

A. At the center of the Earth.
Explanation
If the Earth had two identical moons in one circular orbit and they were as far apart as possible, the center of gravity of the Earth-moons system would be at the center of the Earth. This is because the center of gravity is the point where the gravitational forces acting on the system balance out. In this scenario, the gravitational forces from the two moons would be equal and opposite, causing them to cancel each other out and resulting in the center of gravity being at the center of the Earth.

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• 29.

### A carnival has a Ferris wheel where the seats are located halfway between the center and outside rim. If you were at the outside rim, your angular speed while riding on this Ferris wheel would be

• A.

Less and your tangential speed more.

• B.

More and your tangential speed less.

• C.

The same and your tangential speed less.

C. The same and your tangential speed less.
Explanation
When riding on a Ferris wheel, the angular speed is the same for all points on the wheel. This means that no matter where you are on the Ferris wheel, the time it takes for you to complete one revolution is the same. However, the tangential speed, which is the speed at which you are moving in a straight line along the circumference of the wheel, is different at different points on the wheel. Since the seats are located halfway between the center and outside rim, the tangential speed would be less at the outside rim compared to the center. Therefore, the correct answer is that the angular speed is the same and the tangential speed is less at the outside rim.

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• 30.

### When doing somersaults, you'll more easily rotate when your body is

• A.

• B.

Straight with both arms at your sides.

• C.

Balled up.

• D.

No difference

C. Balled up.
Explanation
When doing somersaults, you'll more easily rotate when your body is balled up. This is because when your body is balled up, your mass is concentrated in a smaller area, which allows for faster rotation due to the conservation of angular momentum. Additionally, when your body is balled up, it creates a smaller moment of inertia, making it easier to rotate. Having both arms above your head or at your sides would not provide the same level of compactness and concentration of mass, therefore making it more difficult to rotate.

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• 31.

### A tightrope walker more easily balances on a tightwire if his pole

• A.

Is held high.

• B.

Droops.

• C.

Is short but heavy.

B. Droops.
Explanation
The correct answer is "droops." When a tightrope walker's pole droops, it lowers the center of gravity, making it easier for the walker to maintain balance. This allows them to counteract any potential tipping or swaying movements and stay stable on the tightwire. Holding the pole high would raise the center of gravity, making it more difficult to balance, while a short but heavy pole would not have the same effect as a drooping pole.

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• 32.

### For a system in mechanical equilibrium

• A.

The resultant force must be zero.

• B.

The resultant torques must be zero.

• C.

The resultant forces and torques must both be zero.

• D.

The resultant forces and torques must be equal.

C. The resultant forces and torques must both be zero.
Explanation
In a system in mechanical equilibrium, the forces and torques acting on the system must both be zero. This means that the net force on the system is zero, indicating that the system is not accelerating in any direction. Additionally, the net torque on the system is zero, meaning that there is no rotational acceleration. Therefore, for a system to be in mechanical equilibrium, both the resultant forces and torques acting on it must be zero.

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• 33.

### To turn a stubborn screw, it is best to use a screwdriver that has a

• A.

Wide handle.

• B.

Long handle.

• C.

Smooth handle.

• D.

None of these

A. Wide handle.
Explanation
A wide handle on a screwdriver provides a larger surface area for the hand to grip, allowing for better leverage and control when turning a stubborn screw. This makes it easier to apply more force and torque, reducing the chances of slipping or stripping the screw. A longer handle may provide additional leverage but may also be more difficult to control. A smooth handle does not necessarily provide any advantage in turning a stubborn screw.

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• 34.

### Two people are balanced on a seesaw. If one person leans toward the center of the seesaw, that person's end of the seesaw will

• A.

Rise.

• B.

Fall.

• C.

Stay at the same level.

• D.

Rise and then fall.

• E.

Fall and then rise

A. Rise.
Explanation
When one person leans toward the center of the seesaw, their end of the seesaw will rise. This is because the person's weight is shifting closer to the center of the seesaw, reducing the downward force on their end. As a result, the other end of the seesaw, which has less weight on it, will rise.

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• 35.

### A 1-kg rock is suspended from the tip of a meter stick at the 0-cm mark so that the meter stick balances like a seesaw when the fulcrum is at the 25-cm mark. From this information, what is the mass of the meter stick?

• A.

1/4 kg

• B.

1/2 kg

• C.

3/4 kg

• D.

1 kg

• E.

More than 1 kg

B. 1/2 kg
• 36.

### A ball rolls down a hill mainly because of

• A.

An unbalanced torque.

• B.

A balanced torque.

• C.

Its rotational inertia.

• D.

Its angular acceleration.

• E.

Its angular momentum.

A. An unbalanced torque.
Explanation
The ball rolls down a hill mainly because of an unbalanced torque. Torque is the rotational force that causes an object to rotate. In this case, the unbalanced torque causes the ball to start rolling and continue rolling downhill. If the torque were balanced, the ball would remain stationary or move in a different direction. The other options, such as rotational inertia, angular acceleration, and angular momentum, are related to the motion of the ball but do not directly explain why it rolls down the hill.

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• 37.

### To kick a football so it won't topple end over end, kick it so the force of impact extends

• A.

Above its center of gravity.

• B.

Through its center of gravity.

• C.

Below its center of gravity

B. Through its center of gravity.
Explanation
When a football is kicked through its center of gravity, the force of impact is evenly distributed throughout the ball. This prevents it from toppling end over end because there is no imbalance in the forces acting on it. Kicking the ball above or below its center of gravity would create an uneven distribution of force, causing the ball to rotate and potentially topple. Therefore, kicking through the center of gravity ensures a stable trajectory for the football.

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• 38.

### A car travels in a circle with constant speed. The net force on the car is

• A.

Directed forward, in the direction of travel.

• B.

Directed toward the center of the curve.

• C.

Zero because the car is not accelerating.

• D.

None of these

B. Directed toward the center of the curve.
Explanation
When a car travels in a circle with constant speed, it is constantly changing its direction. According to Newton's second law of motion, an object will experience a net force when it undergoes acceleration. In this case, the car is constantly changing its direction, which means it is undergoing acceleration. Therefore, there must be a net force acting on the car. Since the car is moving in a circle, the net force must be directed toward the center of the curve, allowing the car to continuously change its direction and maintain its circular motion.

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• 39.

### If the Earth rotated more slowly about its axis, your apparent weight would

• A.

Increase.

• B.

Decrease.

• C.

Stay the same.

• D.

Be zero.

A. Increase.
Explanation
If the Earth rotated more slowly about its axis, the centrifugal force acting on objects on the surface would decrease. This force opposes the force of gravity and contributes to the apparent weight of objects. Therefore, if the centrifugal force decreases, the apparent weight of objects would increase.

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• 40.

### Strictly speaking, to weigh less in the Northern Hemisphere, you should move to a location further

• A.

North (toward the pole).

• B.

South (toward the equator).

• C.

East.

• D.

West.

B. South (toward the equator).
Explanation
Moving towards the equator would make you weigh less in the Northern Hemisphere because the Earth's rotation causes a centrifugal force that is strongest at the equator. This force counteracts the gravitational force, making you weigh slightly less. As you move further south towards the equator, the centrifugal force increases, resulting in a decrease in weight.

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• 41.

### A huge rotating cloud of particles in space gravitate together to form an increasingly dense ball. As it shrinks in size, the cloud

• A.

Rotates faster.

• B.

Rotates slower.

• C.

Rotates at the same speed.

• D.

Cannot rotate.

A. Rotates faster.
Explanation
As the cloud of particles in space gravitates together to form a denser ball, the conservation of angular momentum causes it to rotate faster. This is due to the principle of conservation of angular momentum, which states that the product of an object's moment of inertia and its angular velocity remains constant unless acted upon by an external torque. As the cloud shrinks in size, its moment of inertia decreases, causing its angular velocity to increase, resulting in faster rotation.

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• 42.

### If the planet Jupiter underwent gravitational collapse, its rate of rotation about its axis would

• A.

Decrease.

• B.

Increase.

• C.

Stay the same.

• D.

B. Increase.
Explanation
When a planet undergoes gravitational collapse, its size decreases, resulting in a decrease in its moment of inertia. According to the conservation of angular momentum, when the moment of inertia decreases, the rate of rotation about the axis increases to maintain the same angular momentum. Therefore, if Jupiter underwent gravitational collapse, its rate of rotation about its axis would increase.

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• 43.

### If the polar icecaps melted, the resulting water would spread over the entire Earth. This new mass distribution would tend to make the length of a day

• A.

Longer.

• B.

Shorter.

• C.

Stay the same.

• D.

Shorter at first, then longer.

• E.

Longer at first, then shorter.

A. Longer.
Explanation
If the polar icecaps melted, the resulting water would spread over the entire Earth. This would increase the total mass of the Earth, leading to a redistribution of mass. According to the law of conservation of angular momentum, when the mass distribution changes, the rotation of the Earth slows down, resulting in a longer day. Therefore, if the polar icecaps melted, the length of a day would become longer.

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• 44.

### Suppose you are at the center of a large freely-rotating horizontal turntable in a carnival funhouse. As you crawl toward the edge, the angular momentum of you and the turntable

• A.

Decreases.

• B.

Increases.

• C.

Remains the same, but the RPMs decrease.

• D.

Decreases in direct proportion to your decrease in RPMs.

• E.

None of these

C. Remains the same, but the RPMs decrease.
Explanation
As you crawl towards the edge of the turntable, your distance from the axis of rotation increases, which means your linear velocity decreases. However, in order to maintain angular momentum, the product of your linear velocity and the moment of inertia (which depends on your mass and how it is distributed) must remain constant. Therefore, as your linear velocity decreases, the rotational speed of the turntable (measured in RPMs) must also decrease in order to keep the angular momentum constant. Hence, the correct answer is that the angular momentum remains the same, but the RPMs decrease.

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• 45.

### The gravitational field best suited for humans living in an outer space colony is

• A.

Zero.

• B.

G.

• C.

One-quarter g.

• D.

One-half g.

• E.

Three-quarters g.

B. G.
Explanation
The correct answer is g. Humans living in an outer space colony would be best suited with a gravitational field equal to that of Earth, which is denoted as g. This level of gravity is what humans are accustomed to and is necessary for maintaining normal bodily functions and preventing the negative effects of long-term exposure to microgravity, such as bone and muscle loss.

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• 46.

### What is the simulated gravitational field strength half-way between the axis of the Earth and the outside edge where the field strength is g?

• A.

Zero

• B.

G

• C.

One-half g

• D.

Three-quarters g

C. One-half g
Explanation
The simulated gravitational field strength halfway between the axis of the Earth and the outside edge where the field strength is g would be one-half g. This is because the gravitational field strength decreases as you move away from the center of the Earth. At the axis, the field strength is g, but halfway between the axis and the outside edge, the field strength would be half of g.

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• 47.

### A small boy places a rock under the middle of a of a long wood plank, sits near one end and his mother sits near the opposite end. To balance each other

• A.

The mother should move further away from the boy.

• B.

The boy should move closer to his mother.

• C.

Both should move closer to the ends of the plank.

• D.

Both should move closer to the middle of the plank.

• E.

None of the above choices would work.

E. None of the above choices would work.
Explanation
In order for the boy and his mother to balance each other, their weights must be equal and their distances from the pivot point (the rock) must be equal. If the mother moves further away from the boy, her weight will have a greater lever arm and she will exert a greater torque, causing the plank to tilt towards her. Similarly, if the boy moves closer to his mother, his weight will have a smaller lever arm and he will exert a smaller torque, causing the plank to tilt towards his mother. Moving closer to the ends or the middle of the plank would also disrupt the balance. Therefore, none of the above choices would work.

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• 48.

### Stand a meterstick on its end and let go and it rotates to the floor. If you attach a heavy weight to its upper end and repeat, falling time will be

• A.

More.

• B.

Less.

• C.

The same.

A. More.
Explanation
When a meterstick is stood on its end and allowed to fall, it rotates to the floor due to the force of gravity. When a heavy weight is attached to its upper end, it increases the moment of inertia of the meterstick. This means that more force is required to rotate the meterstick and make it fall. As a result, the falling time will be longer compared to when there is no weight attached. Therefore, the correct answer is "more".

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• 49.

### Suppose you put very large-diameter tires on your car. Then, your speedometer will show a speed that is

• A.

Higher than it is actually.

• B.

Lower than it is actually.

• C.

The same as before.

B. Lower than it is actually.
Explanation
When you put very large-diameter tires on your car, the circumference of the tires increases. This means that for each rotation of the tire, the car will travel a greater distance compared to when it had smaller tires. However, the speedometer is calibrated based on the assumption that the car has the standard-sized tires. As a result, the speedometer will still measure the rotations of the tires, but it will incorrectly calculate the speed based on the assumption of the original tire size. Therefore, the speedometer will show a speed that is lower than it is actually.

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• 50.

### A flywheel's mass is twice that of another of the same size and shape. The more massive flywheel's rotational inertia is

• A.

Four times the other's.

• B.

Two times the other's.

• C.

The same as the other's.

• D.

Half the other's.

B. Two times the other's.
Explanation
The rotational inertia of a flywheel is directly proportional to its mass. Since the more massive flywheel has a mass that is twice that of the other flywheel, its rotational inertia will also be twice as much. Therefore, the correct answer is that the more massive flywheel's rotational inertia is two times the other's.

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• Current Version
• Mar 07, 2024
Quiz Edited by
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• Oct 15, 2012
Quiz Created by
Drtaylor

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