Forces Motion And Energy: Chapter 2, Forces In Motion
Practice quiz for Holt Science and Technology: Forces Motion and Energy: Chapter 2, Forces in Motion
Questions and Answers
- 1.
Which falls faster if there is no air resistance?
- A.
Heavier objects
- B.
Bigger objects
- C.
All ojects fall at the same speed
Correct Answer
C. All ojects fall at the same speedExplanation
In the absence of air resistance, all objects fall at the same speed regardless of their weight or size. This is because the force of gravity acts on all objects equally, causing them to accelerate towards the Earth at the same rate. This principle is known as the equivalence principle and was famously demonstrated by Galileo in his experiments with dropping different objects from the Leaning Tower of Pisa.Rate this question:
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- 2.
Who proved that objects of different mass fall at the same rate by dropping two cannonballs of different masses from the top of the leaning tower of Piza. The crowd was surprised to see that the two cannonballs reached the ground at the same time.
- A.
Newton
- B.
Galileo
- C.
Aristotle
Correct Answer
B. GalileoExplanation
Galileo proved that objects of different mass fall at the same rate by dropping two cannonballs of different masses from the top of the leaning tower of Piza. The fact that the two cannonballs reached the ground at the same time surprised the crowd, indicating that mass does not affect the rate of falling objects. This experiment contradicted Aristotle's belief that heavier objects fall faster than lighter objects. Newton, although a prominent figure in physics, did not specifically prove this concept of objects falling at the same rate regardless of mass.Rate this question:
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- 3.
All objects accellerate toward the earth at __________.
- A.
9.8 meters per second
- B.
8.9 Meters per second per second
- C.
9.8 meters per second per second
Correct Answer
C. 9.8 meters per second per secondExplanation
The correct answer is 9.8 meters per second per second. This is because of the force of gravity, which causes all objects to accelerate towards the Earth at a rate of 9.8 meters per second per second. This means that for every second an object is falling, its velocity increases by 9.8 meters per second.Rate this question:
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- 4.
If there were no air, how fast would a ball be falling toward the earth after 10 seconds?
- A.
V = t - g so 10s - 9.8m/s/s = .2 m/s
- B.
V = t /g so 10s/9.8m/s/s = 1.02 m/s
- C.
V = t x g so 10s x 9.8m/s/s = 98 m/s
Correct Answer
C. V = t x g so 10s x 9.8m/s/s = 98 m/sExplanation
The correct answer is 98 m/s. This is because the equation v = t x g is used, where v represents the velocity, t represents the time, and g represents the acceleration due to gravity. In this case, after 10 seconds, the ball would be falling towards the earth at a velocity of 98 m/s.Rate this question:
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- 5.
If you were to drop a feather and a marble right now, the marble will fall fall faster. Why?
- A.
Air resistance
- B.
The marble is heavier
- C.
The feather is from a bird and birds fly
Correct Answer
A. Air resistanceExplanation
Air resistance is the most likely explanation for why the marble falls faster than the feather. Air resistance is the force that opposes the motion of objects through the air. The feather has a larger surface area and is more affected by air resistance compared to the marble, which has a smaller surface area. Therefore, the feather experiences more air resistance, causing it to fall slower than the marble.Rate this question:
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- 6.
Air resistance is a kind of _______.
- A.
Sliding friction
- B.
Fluid friction
- C.
Rolling friction
Correct Answer
B. Fluid frictionExplanation
Air resistance is a kind of fluid friction. Fluid friction refers to the resistance encountered by an object moving through a fluid, such as air or water. In the case of air resistance, it is the force that opposes the motion of an object through the air. As an object moves through the air, it experiences resistance due to the collision of air molecules with its surface. This resistance depends on factors such as the speed and shape of the object, as well as the density and viscosity of the air.Rate this question:
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- 7.
How would you calculate the force acting on a falling object?
- A.
The force of gravity multiplied by the force of air resistance
- B.
The force of gravity divided by the force of air resistance
- C.
The force of gravity minus the force of air resistance
Correct Answer
C. The force of gravity minus the force of air resistanceExplanation
When a falling object is in motion, it experiences two opposing forces: gravity pulling it downwards and air resistance pushing against it. To calculate the net force acting on the object, we need to consider these two forces. Since the force of air resistance opposes the force of gravity, we subtract the force of air resistance from the force of gravity to determine the net force acting on the falling object.Rate this question:
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- 8.
define terminatl velocity
- A.
When something falls at a constant rate because the downward force of gravity equals the upward force of air resistance
- B.
the velocity of a train as it passes the terminal
- C.
The velocity of an object after it has come to rest on the ground
Correct Answer
A. When something falls at a constant rate because the downward force of gravity equals the upward force of air resistanceExplanation
Terminal velocity is the maximum velocity that an object can achieve when falling through a fluid, such as air, due to the balance between the downward force of gravity and the upward force of air resistance. When an object reaches terminal velocity, it falls at a constant rate without accelerating further. This occurs when the gravitational force pulling the object downwards is equal to the resistance force exerted by the fluid in the opposite direction.Rate this question:
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- 9.
What two factors determine the amount of air resistance.
- A.
Size and mass
- B.
Shape and mass
- C.
Size and shape
Correct Answer
C. Size and shapeExplanation
The amount of air resistance is determined by the size and shape of an object. The size of the object affects the surface area that comes into contact with the air, while the shape determines how the air flows around the object. A larger size or a shape that creates more drag will result in greater air resistance. Similarly, a smaller size or a streamlined shape will result in less air resistance. Therefore, both size and shape play a crucial role in determining the amount of air resistance an object experiences.Rate this question:
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- 10.
Why does an astronaut appear to loat inside the spacecraft?
- A.
The astronaut is weightless
- B.
Both the astronaut and the spacecraft are in free fall.
- C.
They are in outer space where there is no gravity
Correct Answer
B. Both the astronaut and the spacecraft are in free fall.Explanation
When both the astronaut and the spacecraft are in free fall, they are essentially falling towards the Earth at the same rate. This creates a sensation of weightlessness for the astronaut, as they no longer feel the force of gravity pulling them down. As a result, they appear to float inside the spacecraft because there is no external force acting on them to keep them grounded.Rate this question:
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- 11.
Define free fall.
- A.
When gravity is pulling an object down and no other forces are acting on it.
- B.
When something is falling out of an airplane
- C.
When something is falling, but it is weightless
Correct Answer
A. When gravity is pulling an object down and no other forces are acting on it.Explanation
Free fall is defined as the state in which an object is being pulled down by gravity without any other forces acting on it. This means that the object is not being pushed or pulled by any other external force, resulting in a purely gravitational acceleration. It does not necessarily involve an object falling out of an airplane or being weightless, as these conditions may have other forces acting upon the object.Rate this question:
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- 12.
define orbit.
- A.
When something is travelling in a straight path
- B.
When something is traveling in a curved path
- C.
When something is travelling in a circular or near circular path around something else.
Correct Answer
C. When something is travelling in a circular or near circular path around something else.Explanation
An orbit is defined as the path that an object takes when it travels in a circular or near circular path around another object. This can be seen in celestial bodies like planets orbiting around the sun or moons orbiting around a planet. The key characteristic of an orbit is that it follows a curved path rather than a straight line.Rate this question:
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- 13.
What two motions combine to cause one object to orbit another?
- A.
Constant forward motion and free fall
- B.
Constant circular motion and free fall
- C.
Constant forward motion and constant circular motion
Correct Answer
A. Constant forward motion and free fallExplanation
The correct answer is constant forward motion and free fall. In order for an object to orbit another, it must have a constant forward motion to maintain its velocity and prevent it from falling into the object it is orbiting. At the same time, the object must also be in a state of free fall, meaning it is constantly accelerating towards the object due to gravity. These two motions combined create a balanced force that allows the object to continuously orbit around the other.Rate this question:
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- 14.
Define projectile motion.
- A.
When something is travelling in a circular or near circular path around something else.
- B.
The vibration of a projectile
- C.
The curved path an oject follows when it is thrown or propelled near the surface of the earth.
Correct Answer
C. The curved path an oject follows when it is thrown or propelled near the surface of the earth.Explanation
Projectile motion refers to the curved path that an object follows when it is thrown or propelled near the surface of the earth. This type of motion occurs when an object is launched into the air with an initial velocity and then moves under the influence of gravity. The object follows a parabolic trajectory, with its path being influenced by both horizontal and vertical components of motion. This concept is commonly observed in activities such as throwing a ball, shooting a projectile, or the motion of a rocket.Rate this question:
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- 15.
Projectile motion results from combining two motions. What are they?
- A.
Accelerating horizontal motion and constant vertical motion
- B.
Constant horizontal motion and vertical motion accelerating because of gravity
- C.
Free fall and accelerating horizontal motion
Correct Answer
B. Constant horizontal motion and vertical motion accelerating because of gravityExplanation
Projectile motion is the motion of an object that is launched into the air and moves in a curved path under the influence of gravity. It is a combination of two independent motions: constant horizontal motion and vertical motion accelerating due to gravity. The object continues to move horizontally at a constant velocity while simultaneously accelerating downward due to the force of gravity. This combination of motions results in the curved trajectory observed in projectile motion.Rate this question:
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- 16.
Which law is this: The accelleration of an object depends on the mass of the object and the force applied.
- A.
Newtons First Law of motion
- B.
Newton's second law of motion
- C.
Newton's third law of motion
Correct Answer
B. Newton's second law of motionExplanation
Newton's second law of motion states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. This means that the greater the force applied to an object, the greater its acceleration will be, and the greater the mass of the object, the smaller its acceleration will be for a given force. Therefore, the given statement aligns with Newton's second law of motion.Rate this question:
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- 17.
Which law is this: Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.
- A.
Newtons First law of motion
- B.
Newton's second law of motion
- C.
Newton's third law of motion
Correct Answer
C. Newton's third law of motionExplanation
This statement describes Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. It explains that when one object exerts a force on another object, the second object will exert a force of equal magnitude but in the opposite direction on the first object. This law helps to understand the concept of forces and their interactions in the physical world.Rate this question:
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- 18.
How does a rocket engine work and which of Newton's laws of motion is involved.
- A.
The rocket engine pushes gases downward so the gases push the rocket upward with an equal force. Newton's Third Law
- B.
The gases flying out of the rocket engine push against the ground. Newton's Second law.
- C.
Heat rises. Newton's First Law.
Correct Answer
A. The rocket engine pushes gases downward so the gases push the rocket upward with an equal force. Newton's Third LawExplanation
A rocket engine works by pushing gases downward, which in turn pushes the rocket upward with an equal force. This is explained by Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. In this case, the action is the gases being pushed downward by the rocket engine, and the reaction is the rocket being pushed upward.Rate this question:
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- 19.
Which Law is this: An object at rest remains at rest and an object in motion remains in motion at a constant speed and in a straight line unless acted upon by an unbalanced force.
- A.
Newton's first law of motion
- B.
Newton's second law of Motion
- C.
Newton's third law of motion
Correct Answer
A. Newton's first law of motionExplanation
This statement describes Newton's first law of motion, also known as the law of inertia. It states that an object will remain at rest or continue to move with a constant speed and direction unless an external force acts upon it. This law explains the concept of inertia, which is the tendency of an object to resist changes in its motion.Rate this question:
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- 20.
If you were to throw a ball right now, why wouldn't it travel in a straight line forever?
- A.
Because unbalanced forces act on it.
- B.
Because of gravity and air resistance.
- C.
All of the above. Gravity and air resistance provide the unbalanced forces.
Correct Answer
C. All of the above. Gravity and air resistance provide the unbalanced forces.Explanation
When a ball is thrown, it experiences unbalanced forces such as gravity and air resistance. Gravity pulls the ball downwards, causing it to fall towards the ground instead of continuing in a straight line. Air resistance, on the other hand, acts in the opposite direction of the ball's motion, slowing it down and causing it to eventually come to a stop. These two forces combined prevent the ball from traveling in a straight line forever, making "all of the above" the correct answer.Rate this question:
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- 21.
Define inertia.
- A.
The tendancy of all objects to resist any change in motion.
- B.
Change in speed over a period of time.
Correct Answer
A. The tendancy of all objects to resist any change in motion.Explanation
Inertia is defined as the tendency of all objects to resist any change in motion. This means that objects at rest will stay at rest, and objects in motion will continue moving at a constant velocity unless acted upon by an external force. Inertia is a fundamental property of matter and is related to an object's mass. The greater the mass of an object, the greater its inertia and resistance to changes in motion.Rate this question:
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- 22.
Between two objects, which will have more inertia?
- A.
The one with less mass
- B.
The one that is traveling faster
- C.
The one with more mass
Correct Answer
C. The one with more massExplanation
The object with more mass will have more inertia because inertia is directly proportional to mass. Inertia is the resistance of an object to changes in its state of motion, and a larger mass means a greater resistance to changes in motion. Therefore, the object with more mass will require more force to accelerate or decelerate compared to the object with less mass.Rate this question:
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- 23.
What determines how much an object will accellerate?
- A.
The amount of force acting on the object
- B.
The mass of the object
- C.
Both the mass of the object and the force acting on it
Correct Answer
C. Both the mass of the object and the force acting on itExplanation
The acceleration of an object is determined by both the mass of the object and the force acting on it. According to Newton's second law of motion, the acceleration of an object is directly proportional to the force applied to it and inversely proportional to its mass. This means that the greater the force applied to an object, the greater its acceleration will be. Similarly, the smaller the mass of an object, the greater its acceleration will be for a given force. Therefore, both the mass of the object and the force acting on it play a role in determining its acceleration.Rate this question:
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- 24.
How do you state Newton's second law mathematically? (a = accelleration; m = mass; f = force)
- A.
A = f x m
- B.
A = f / m
- C.
A = f + m
- D.
A = f - m
Correct Answer
B. A = f / mExplanation
Newton's second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Mathematically, this can be represented as a = f / m, where "a" represents acceleration, "f" represents force, and "m" represents mass. This equation shows that the acceleration of an object is equal to the force applied divided by its mass.Rate this question:
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- 25.
What is a second way of stating newton's second law mathematically?
- A.
F = m x a
- B.
F = m - a
- C.
F = m / a
Correct Answer
A. F = m x aExplanation
The correct answer is f = m x a. This is because Newton's second law states that the force acting on an object is equal to the mass of the object multiplied by its acceleration. Therefore, the mathematical representation of this law is f = m x a, where f represents force, m represents mass, and a represents acceleration.Rate this question:
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- 26.
Define momentum.
- A.
A property of a moving object that depends upon its mass and velocity.
- B.
The time it takes to stop a moving object
- C.
Inertia
Correct Answer
A. A property of a moving object that depends upon its mass and velocity.Explanation
Momentum is a property of a moving object that depends on both its mass and velocity. It is a measure of the object's motion and is directly proportional to both mass and velocity. In other words, an object with a larger mass or a higher velocity will have a greater momentum. This concept is important in understanding the behavior of moving objects, such as collisions, and is a fundamental principle in physics.Rate this question:
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- 27.
Which has more momentum:
- A.
A 5 gram marble moving at 60 miles per hour
- B.
A 10 gram marble moving at 60 miles per hour
- C.
A 10 gram marble moving at 10 miles per hour
Correct Answer
B. A 10 gram marble moving at 60 miles per hourExplanation
The momentum of an object is given by the product of its mass and velocity. In this case, we have two marbles with different masses and velocities. The momentum of an object is directly proportional to its mass, so the 10 gram marble will have more momentum than the 5 gram marble. Additionally, both marbles have the same velocity of 60 miles per hour, so the velocity does not affect the comparison of momentum. Therefore, the 10 gram marble moving at 60 miles per hour has more momentum than the 5 gram marble.Rate this question:
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- 28.
If one marble strikes another marble, some momentum wil be transfered from one to the other. What will happen to their combined momentum.
- A.
It will increase
- B.
It will decrease
- C.
It will stay the same
Correct Answer
C. It will stay the sameExplanation
When one marble strikes another marble, momentum is transferred from one to the other. However, according to the law of conservation of momentum, the total momentum of a system remains constant if no external forces are acting on it. Therefore, the combined momentum of the two marbles will stay the same.Rate this question:
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- 29.
Which law do you use to answer the previous question?
- A.
The law of the conservation of momentum
- B.
Newton's first law of motion
- C.
Newton's second law of motion
Correct Answer
A. The law of the conservation of momentumExplanation
The law of the conservation of momentum is used to answer the previous question. This law states that the total momentum of a closed system remains constant unless acted upon by an external force. In the context of the previous question, the law of conservation of momentum would be used to analyze the momentum of the system and determine its overall conservation or any changes that occur. Newton's first and second laws of motion are not relevant to this question.Rate this question:
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