Question 1

An object is moving with constant non-zero acceleration in the +x direction. The velocity versus time graph of this object is
A)a horizontal straight line.
B)a vertical straight line.
C)a straight line making an angle with the time axis.
D)a parabolic curve.

Accepted Answer

Since the object is moving with constant non-zero acceleration in the +x direction, the velocity versus time graph must be a straight line. However, this straight line cannot be horizontal or vertical because the velocity is changing over time. Therefore, the only option left is a straight line making an angle with the time axis.

Question 2

Two objects are dropped from a bridge, an interval of 1.0 s apart. Air resistance is negligible. During the time that both objects continue to fall, their separation
A)increases.
B)decreases.
C)stays constant.
D)increases at first, but then stays constant.
E)decreases at first, but then stays constant.

Accepted Answer

Since air resistance is negligible, both objects accelerate at the same rate due to gravity. The second object starts falling 1 second later, so the first object has a head start. As both accelerate equally, the distance between them increases over time.

Question 3

Two objects are thrown from the top of a tall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street? Neglect air resistance.
A)The one thrown up is traveling faster.
B)The one thrown down is traveling faster.
C)They are traveling at the same speed.
D)It is impossible to tell because the height of the building is not given.

Accepted Answer

The objects will have the same speed when they hit the street because they both experience the same acceleration due to gravity, which is independent of the direction of motion. The initial velocity only determines how long it takes for each object to reach the street, not their final speed. The height of the building is not needed to determine their final speed.

Question 4

An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is
A)a horizontal straight line.
B)a vertical straight line.
C)a straight line making an angle with the time axis.
D)a parabolic curve.

Accepted Answer

Since the object is moving with a constant non-zero velocity in the +x direction, its velocity is not changing with time. Therefore, the graph of its velocity versus time will be a horizontal straight line.

Question 5

An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is
A)a horizontal straight line.
B)a vertical straight line.
C)a straight line making an angle with the time axis.
D)a parabolic curve.

Accepted Answer

A constant non-zero velocity means the object is moving at a steady rate in the +x direction. This results in a position vs. time graph that is a straight line making an angle with the time axis, where the slope of the line represents the velocity.

Question 6

A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v₀ and experience no significant air resistance. If the 10-kg rock reaches a maximum height h, what maximum height will the 20-kg ball reach? A)h/4 B)h/2 C)h D)2h E)4h

Accepted Answer

The maximum height reached by a projectile launched with initial speed v is h = v^2/2g (where g is the acceleration due to gravity). Since both rocks are launched with the same initial speed and experience the same acceleration due to gravity, the maximum height reached by the 20-kg rock will be the same as the maximum height reached by the 10-kg rock, which is h. Therefore, the answer is choice C.

Question 7

The slope of a velocity versus time graph gives
A)the distance traveled.
B)velocity.
C)acceleration.
D)displacement.

Accepted Answer

The slope of a velocity versus time graph gives the rate of change of velocity, which is acceleration. Therefore, C is the best choice. The other choices are not correct because the velocity versus time graph does not directly give information about distance traveled (which would require integrating the graph to find the area underneath), velocity (which is represented directly on the graph, not calculated from the slope), or displacement (which would require additional information such as initial position).

Question 8

Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point?
A)zero
B)slightly less than g
C)exactly g
D)slightly greater than g

Accepted Answer

The acceleration of the ball is exactly g (9.8 m/s^2 downward) throughout its flight, including just before it reaches its highest point, due to gravity.

Question 9

A ball is thrown straight up, reaches a maximum height, then falls to its initial height. Which of the following statements about the direction of the velocity and acceleration of the ball as it is going up is correct?
A)Both its velocity and its acceleration point upward.
B)Its velocity points upward and its acceleration points downward.
C)Its velocity points downward and its acceleration points upward.
D)Both its velocity and its acceleration points downward.

Accepted Answer

As the ball is thrown straight up, its initial velocity is upward. As it moves up, the gravitational force acts on it, causing its acceleration to be directed downward. Therefore, its velocity points upward (in the direction of its initial motion) and its acceleration points downward (in the direction of the gravitational force).

Question 10

Ball A is dropped from the top of a building. One second later, ball B is dropped from the same building. Neglect air resistance. As time progresses, the difference in their speeds
A)increases.
B)remains constant.
C)decreases.
D)cannot be determined from the information given.

Accepted Answer

Since both balls are being dropped from the same height and neglecting air resistance, they will experience the same acceleration due to gravity of 9.8 m/s^2. Therefore, their speeds will increase at the same rate and remain constant relative to each other, meaning the difference in their speeds will remain constant as well.

Question 11

From the edge of a roof top you toss a green ball upwards with initial speed v₀ and a blue ball downwards with the same initial speed. Air resistance is negligible. When they reach the ground below A)the green ball will be moving faster than the blue ball. B)the blue ball will be moving faster than the green ball. C)the two balls will have the same speed.

Accepted Answer

Assuming that both balls are released at the same time from the same height, they will both experience the same acceleration due to gravity (9.8 m/s^2 downward). However, since the green ball is thrown upwards, it will initially have a positive vertical velocity and the blue ball will initially have a negative vertical velocity. As they both fall towards the ground, their velocities will decrease due to gravity, but their velocities will have opposite signs.

At some point, the green ball will reach its maximum height and its vertical velocity will be zero. From the conservation of energy, we know that its initial kinetic energy (1/2 mv^2) is equal to its potential energy at maximum height (mgh), where m is the mass of the ball, v is its velocity, and h is the height from which it was thrown. Since the blue ball was thrown with the same initial velocity, it will also have the same kinetic energy as the green ball at the maximum height.

When they both hit the ground, their potential energy is zero and they both have kinetic energy equal to the initial kinetic energy. Since they both have the same initial kinetic energy and the same mass, they will both have the same speed when they hit the ground. Thus, the answer is C - the two balls will have the same speed.

Question 12

An object is moving with constant non-zero acceleration in the +x direction. The position versus time graph of this object is
A)a horizontal straight line.
B)a vertical straight line.
C)a straight line making an angle with the time axis.
D)a parabolic curve.

Accepted Answer

Since the object has a constant non-zero acceleration in the +x direction, its velocity is changing at a constant rate. This means that the slope of the position versus time graph (which represents the velocity) is changing at a constant rate. Therefore, the graph must be a curve, and specifically a parabolic curve.

Question 13

Brick A is dropped from the top of a building. Brick B is thrown straight down from the same building, and neither one experiences appreciable air resistance. Which statement about their accelerations is correct?
A)The acceleration of A is greater than the acceleration of B.
B)The acceleration of B is greater than the acceleration of A.
C)The two bricks have exactly the same acceleration.
D)Neither brick has any acceleration once it is released.

Accepted Answer

The acceleration of both the bricks will be equal because the acceleration due to gravity is the same for all objects, regardless of their mass or initial velocity. The acceleration due to gravity is approximately 9.8 m/s^2. Therefore, both the bricks will have an acceleration of 9.8 m/s^2 towards the ground.

Question 14

A rock from a volcanic eruption is launched straight up into the air with no appreciable air resistance. Which one of the following statements about this rock while it is in the air is correct?
A)On the way up, its acceleration is downward and its velocity is upward, and at the highest point both its velocity and acceleration are zero.
B)On the way down, both its velocity and acceleration are downward, and at the highest point both its velocity and acceleration are zero.
C)Throughout the motion, the acceleration is downward, and the velocity is always in the same direction as the acceleration.
D)The acceleration is downward at all points in the motion.
E)The acceleration is downward at all points in the motion except that is zero at the highest point.

Accepted Answer

The acceleration due to gravity is always downward throughout the motion of the rock, regardless of whether the rock is moving up, at its highest point, or coming down.

Question 15

A 10-kg rock and a 20-kg rock are dropped at the same time and experience no significant air resistance. If the 10-kg rock falls with acceleration a, what is the acceleration of the 20-kg rock?
A)4a
B)2a
C)a
D)a/2
E)a/4

Accepted Answer

According to the principle of free fall, all objects close to the surface of the earth will experience the same acceleration due to gravity, which is approximately 9.8 m/s^2. Therefore, the acceleration of the 20-kg rock will also be a, the same as the 10-kg rock. Choice A, B, D, and E are incorrect because they involve a different acceleration than a.

Question 16

A ball is thrown downward in the absence of air resistance. After it has been released, which statement(s)concerning its acceleration is correct? (There could be more than one correct choice.)
A)Its acceleration is constantly increasing.
B)Its acceleration is constant.
C)Its acceleration is constantly decreasing.
D)Its acceleration is zero.
E)Its acceleration is greater than g.

Accepted Answer

In the absence of air resistance, the only force acting on the ball is gravity, which imparts a constant acceleration equal to g (9.8 m/s^2 on Earth). This means the acceleration does not change over time, making it constant.

Question 17

The slope of a position versus time graph gives
A)the distance traveled.
B)velocity.
C)acceleration.
D)displacement.

Accepted Answer

The slope of a position versus time graph gives the rate at which position is changing, which is velocity. Therefore, the best choice is B.

Question 18

When a ball is thrown straight up with no air resistance, the acceleration at its highest point
A)is upward
B)is downward
C)is zero
D)reverses from upward to downward
E)reverses from downward to upward

Accepted Answer

The acceleration due to gravity is always directed downward, regardless of the object's motion. At the highest point, the velocity of the ball is zero, but the acceleration remains directed downward at approximately 9.8 m/s^2.

Question 19

If the position versus time graph of an object is a horizontal line, the object is
A)moving with constant non-zero speed.
B)moving with constant non-zero acceleration.
C)at rest.
D)moving with increasing speed.

Accepted Answer

A horizontal line on a position versus time graph indicates that the position of the object does not change as time progresses, meaning the object is at rest.

Question 20

A 10-kg rock and 20-kg rock are dropped from the same height and experience no significant air resistance. If it takes the 20-kg rock a time T to reach the ground, what time will it take the 10-kg rock to reach the ground?
A)4T
B)2T
C)T
D)T/2
E)T/4

Accepted Answer

Both rocks experience the same acceleration due to gravity, which means their time to reach the ground is solely dependent on the initial height from which they are dropped. Therefore, both rocks will take the same amount of time to reach the ground, which is T.

Quiz 2: Motion in One Dimension

An object is moving with constant non-zero acceleration in the +x direction. The velocity versus time graph of this object is

Two objects are dropped from a bridge, an interval of 1.0 s apart. Air resistance is negligible. During the time that both objects continue to fall, their separation

Two objects are thrown from the top of a tall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street? Neglect air resistance.

An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is

An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is

A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v₀ and experience no significant air resistance. If the 10-kg rock reaches a maximum height h, what maximum height will the 20-kg ball reach?

The slope of a velocity versus time graph gives

Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point?

A ball is thrown straight up, reaches a maximum height, then falls to its initial height. Which of the following statements about the direction of the velocity and acceleration of the ball as it is going up is correct?

Ball A is dropped from the top of a building. One second later, ball B is dropped from the same building. Neglect air resistance. As time progresses, the difference in their speeds

From the edge of a roof top you toss a green ball upwards with initial speed v₀ and a blue ball downwards with the same initial speed. Air resistance is negligible. When they reach the ground below

An object is moving with constant non-zero acceleration in the +x direction. The position versus time graph of this object is

Brick A is dropped from the top of a building. Brick B is thrown straight down from the same building, and neither one experiences appreciable air resistance. Which statement about their accelerations is correct?

A rock from a volcanic eruption is launched straight up into the air with no appreciable air resistance. Which one of the following statements about this rock while it is in the air is correct?

A 10-kg rock and a 20-kg rock are dropped at the same time and experience no significant air resistance. If the 10-kg rock falls with acceleration a, what is the acceleration of the 20-kg rock?

A ball is thrown downward in the absence of air resistance. After it has been released, which statement(s) concerning its acceleration is correct? (There could be more than one correct choice.)

The slope of a position versus time graph gives

When a ball is thrown straight up with no air resistance, the acceleration at its highest point

If the position versus time graph of an object is a horizontal line, the object is

A 10-kg rock and 20-kg rock are dropped from the same height and experience no significant air resistance. If it takes the 20-kg rock a time T to reach the ground, what time will it take the 10-kg rock to reach the ground?