# Chapter 5: Circular Motion; Gravitation

80 Questions | Total Attempts: 1356  Settings  • 1.
Is it possible for an object moving with a constant speed to accelerate? Explain.
• A.

No, if the speed is constant then the acceleration is equal to zero.

• B.

No, an object can accelerate only if there is a net force acting on it.

• C.

Yes, although the speed is constant, the direction of the velocity can be changing.

• D.

Yes, if an object is moving it can experience acceleration.

• 2.
Consider a particle moving with constant speed such that its acceleration of constant magnitude is always perpendicular to its velocity.
• A.

It is moving in a straight line.

• B.

It is moving in a circle.

• C.

It is moving in a parabola.

• D.

None of the above is definitely true all of the time.

• 3.
An object moves in a circular path at a constant speed. Compare the direction of the object's velocity and acceleration vectors.
• A.

Both vectors point in the same direction.

• B.

The vectors point in opposite directions.

• C.

The vectors are perpendicular.

• D.

The question is meaningless, since the acceleration is zero.

• 4.
When an object experiences uniform circular motion, the direction of the acceleration is
• A.

In the same direction as the velocity vector.

• B.

In the opposite direction of the velocity vector.

• C.

Is directed toward the center of the circular path.

• D.

Is directed away from the center of the circular path.

• 5.
Consider a particle moving with constant speed such that its acceleration of constant magnitude is always perpendicular to its velocity.
• A.

It is moving in a straight line.

• B.

It is moving in a circle.

• C.

It is moving in a parabola.

• D.

None of the above is definitely true all of the time.

• 6.
What type of acceleration does an object moving with constant speed in a circular path experience?
• A.

Free fall

• B.

Constant acceleration

• C.

Linear acceleration

• D.

Centripetal acceleration

• 7.
What force is needed to make an object move in a circle?
• A.

Kinetic friction

• B.

Static friction

• C.

Centripetal force

• D.

Weight

• 8.
When an object experiences uniform circular motion, the direction of the net force is
• A.

In the same direction as the motion of the object.

• B.

In the opposite direction of the motion of the object.

• C.

Is directed toward the center of the circular path.

• D.

Is directed away from the center of the circular path.

• 9.
A roller coaster car is on a track that forms a circular loop in the vertical plane. If the car is to just maintain contact with track at the top of the loop, what is the minimum value for its centripetal acceleration at this point?
• A.

G downward

• B.

0.5g downward

• C.

G upward

• D.

2g upward

• 10.
A roller coaster car (mass = M) is on a track that forms a circular loop (radius = r) in the vertical plane. If the car is to just maintain contact with the track at the top of the loop, what is the minimum value for its speed at that point?
• A.

Rg

• B.

(rg)1/2

• C.

(2rg)1/2

• D.

(0.5rg)1/2

• 11.
A pilot executes a vertical dive then follows a semi-circular arc until it is going straight up. Just as the plane is at its lowest point, the force on him is
• A.

Less than mg, and pointing up.

• B.

Less than mg, and pointing down.

• C.

More than mg, and pointing up.

• D.

More than mg, and pointing down.

• 12.
A coin of mass m rests on a turntable a distance r from the axis of rotation. The turntable rotates with a frequency of f. What is the minimum coefficient of static friction between the turntable and the coin if the coin is not to slip?
• A.

(4π^2f^2r)/g

• B.

(4π^2fr^2)/g

• C.

(4πf^2r)/g

• D.

(4πfr^2)/g

• 13.
A car goes around a curve of radius r at a constant speed v. What is the direction of the net force on the car?
• A.

Toward the curve's center

• B.

Away from the curve's center

• C.

Toward the front of the car

• D.

Toward the back of the car

• 14.
A car goes around a curve of radius r at a constant speed v. Then it goes around the same curve at half of the original speed. What is the centripetal force on the car as it goes around the curve for the second time, compared to the first time?
• A.

Twice as big

• B.

Four times as big

• C.

Half as big

• D.

One-fourth as big

• 15.
A car goes around a curve of radius r at a constant speed v. Then it goes around a curve of radius 2r at speed 2v. What is the centripetal force on the car as it goes around the second curve, compared to the first?
• A.

Four times as big

• B.

Twice as big

• C.

One-half as big

• D.

One-fourth as big

• 16.
A car of mass m goes around a banked curve of radius r with speed v. If the road is frictionless due to ice, the car can still negotiate the curve if the horizontal component of the normal force on the car from the road is equal in magnitude to
• A.

Mg/2.

• B.

Mg.

• C.

Mv^2/r.

• D.

Tan[v^2/(rg)].

• 17.
Two horizontal curves on a bobsled run are banked at the same angle, but one has twice the radius of the other. The safe speed (no friction needed to stay on the run) for the smaller radius curve is v. What is the safe speed on the larger radius curve?
• A.

Approximately 0.707v

• B.

2v

• C.

Approximately 1.41v

• D.

0.5v

• 18.
The banking angle in a turn on the Olympic bobsled track is not constant, but increases upward from the horizontal. Coming around a turn, the bobsled team will intentionally "climb the wall," then go lower coming out of the turn. Why do they do this?
• A.

To give the team better control, because they are able to see ahead of the turn

• B.

To prevent the bobsled from turning over

• C.

To take the turn at a faster speed

• D.

To reduce the g-force on them

• 19.
Is it possible for an object moving around a circular path to have both centripetal and tangential acceleration?
• A.

No, because then the path would not be a circle.

• B.

No, an object can only have one or the other at any given time.

• C.

Yes, this is possible if the speed is constant.

• D.

Yes, this is possible if the speed is changing.

• 20.
The gravitational force between two objects is proportional to
• A.

The distance between the two objects.

• B.

The square of the distance between the two objects.

• C.

The product of the two objects.

• D.

The square of the product of the two objects.

• 21.
The gravitational force between two objects is inversely proportional to
• A.

The distance between the two objects.

• B.

The square of the distance between the two objects.

• C.

The product of the two objects.

• D.

The square of the product of the two objects.

• 22.
Two objects attract each other gravitationally. If the distance between their centers is cut in half, the gravitational force
• A.

Is cut to one fourth.

• B.

Is cut in half.

• C.

Doubles.

• D.

• 23.
Compared to its mass on the Earth, the mass of an object on the Moon is
• A.

Less.

• B.

More.

• C.

The same.

• D.

Half as much.

• 24.
The acceleration of gravity on the Moon is one-sixth what it is on Earth. An object of mass 72 kg is taken to the Moon. What is its mass there?
• A.

12 kg

• B.

72 kg

• C.

72 N

• D.

12 N

• 25.
As a rocket moves away from the Earth's surface, the rocket's weight
• A.

Increases.

• B.

Decreases.

• C.

Remains the same.

• D.

Depends on how fast it is moving.

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