Question 1

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) stays constant.
B) increases at first, but then stays constant.
C) decreases.
D) decreases at first, but then stays constant.
E) increases.

Accepted Answer

Since both objects are accelerating due to gravity at the same rate, the second object will continue to fall at an increasing velocity starting 1.0 s after the first object. This means the distance between them increases over time, as the second object covers more distance in each subsequent second than the first object did in the corresponding time interval.

Question 2

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) The acceleration is downward at all points in the motion except that is zero at the highest point.
B) 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.
C) On the way down, both its velocity and acceleration are downward, and at the highest point both its velocity and acceleration are zero.
D) The acceleration is downward at all points in the motion.
E) Throughout the motion, the acceleration is downward, and the velocity is always in the same direction as the acceleration.

Accepted Answer

The acceleration due to gravity is always downward throughout the motion of the rock, including at the highest point where the velocity is zero but acceleration remains constant and directed downward.

Question 3

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

Accepted Answer

The answer of From the edge of a roof top...

Question 4

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) 
B) 
C) 
D) 
E)

Accepted Answer

The answer of A 10-kg rock and 20-kg rock are...

Question 5

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct?
A) Since the car is slowing down, its acceleration must be negative.
B) The acceleration is toward the west.
C) The acceleration is zero.
D) The acceleration is toward the east.

Accepted Answer

When a car slows down while traveling west, its acceleration is in the opposite direction of its motion, which means it is toward the east. Acceleration is defined as the rate of change of velocity, and a change in speed or direction means there is acceleration. In this case, the car is decelerating, which is still acceleration but in the opposite direction of its velocity.

Question 6

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

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 7

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) 
B) 
C) 
D) 
E)

Accepted Answer

The answer of A 10-kg rock and a 20-kg rock...

Question 8

An object moving in the  +x  direction experiences an acceleration of    This means the object
A) is decreasing its velocity by  2.0 m/s every second.
B) is traveling at  2.0 m/s.
C) is increasing its velocity by  2.0 m/s every second.
D) travels  2.0 m in every second.

Accepted Answer

The answer of An object moving in the  +x...

Question 9

If the velocity of an object is zero at one instant, what is true about the acceleration of that object? (There could be more than one correct choice.)
A) The acceleration must be zero.
B) The acceleration could be negative.
C) The acceleration could be zero.
D) The acceleration could be positive.

Accepted Answer

An object can have zero velocity at a moment but still be accelerating. This means the acceleration could be positive (speeding up in the positive direction), negative (speeding up in the negative direction), or zero (moving to a stop or starting to move).

Question 10

An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion?
A) average acceleration
B) instantaneous speed
C) instantaneous acceleration
D) average speed
E) displacement

Accepted Answer

The phrase "from zero to sixty in eight seconds" describes how quickly the car's velocity changes over a period of time, which is the definition of average acceleration.

Question 11

Under what condition is average velocity equal to the average of the object's initial and final velocity?
A) The acceleration is constant.
B) The acceleration must be constantly increasing.
C) This can occur only when the velocity is zero.
D) This can only occur if there is no acceleration.
E) The acceleration must be constantly decreasing.

Accepted Answer

Average velocity is equal to the average of the object's initial and final velocity when the acceleration is constant. This is derived from the equation for average velocity under constant acceleration, $v_{avg} = \frac{v_i + v_f}{2}$, where $v_i$ is the initial velocity, $v_f$ is the final velocity, and $v_{avg}$ is the average velocity.

Question 12

Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?
A) Its acceleration is zero.
B) Its acceleration is negative.
C) Its acceleration is decreasing in magnitude as the car slows down.
D) Its acceleration is positive.

Accepted Answer

Since the car is slowing down while traveling west (negative direction), its acceleration is in the opposite direction (east or positive direction) to decrease its velocity.

Question 13

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/4 
D)  a/2 
E)  a

Accepted Answer

Both rocks experience the same acceleration due to gravity, regardless of their mass, assuming no significant air resistance.

Question 14

A racing car accelerates uniformly from rest along a straight track. This track has markers spaced at equal distances along it from the start, as shown in the figure. The car reaches a speed of 140
Km/h as it passes marker 2.  Where on the track was the car when it was traveling at half this speed, that is at 70 km/h?
A) At marker 1
B) Between marker 1 and marker 2
C) Before marker 1

Accepted Answer

The answer of A racing car accelerates uniformly from rest...

Question 15

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) Its velocity points upward and its acceleration points downward.
B) Both its velocity and its acceleration point upward.
C) Its velocity points downward and its acceleration points upward.
D) Both its velocity and its acceleration points downward.

Accepted Answer

When a ball is thrown straight up, its velocity initially points upward as it ascends. However, due to gravity, its acceleration is always downward, towards the center of the Earth. This downward acceleration slows the ball until it reaches its peak, where its velocity is momentarily zero, before it starts to fall back down, accelerating under gravity.

Question 16

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) decreases.
C) remains constant.
D) cannot be determined from the information given.

Accepted Answer

The acceleration due to gravity acts equally on both balls, so the difference in their speeds remains constant. Each ball accelerates at the same rate (9.8 m/s^2), so the speed difference established in the first second is maintained.

Question 17

Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?
A) Its acceleration is zero.
B) Its acceleration is in the -x direction.
C) Its acceleration is in the +x direction.
D) Its acceleration is decreasing in magnitude as the car slows down.

Accepted Answer

When a car slows down while traveling east (or in the +x direction), its acceleration is opposite to its direction of motion, which means it is in the -x direction. Acceleration is defined as the rate of change of velocity, so if the velocity is decreasing in the +x direction, the acceleration must be in the -x direction.

Question 18

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 constant.
B) Its acceleration is greater than g.
C) Its acceleration is constantly decreasing.
D) Its acceleration is zero.
E) Its acceleration is constantly increasing.

Accepted Answer

The acceleration of an object in free fall, or thrown downward without air resistance, is constant and equal to the acceleration due to gravity (g), which is approximately 9.8 m/s^2 on the surface of the Earth.

Question 19

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) exactly g
B) slightly less than g
C) slightly greater than g
D) zero

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 20

Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct?
A) The acceleration is a constant non-zero value.
B) The acceleration is constantly increasing.
C) The acceleration is constantly decreasing.
D) The acceleration is equal to zero.

Accepted Answer

When an object moves with constant velocity, it means there is no change in its speed or direction. Therefore, its acceleration, which is the rate of change of velocity, must be zero.

Quiz 2: Describing Motion: Kinematics in One Dimension

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 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?

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

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?

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct?

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

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?

An object moving in the +x direction experiences an acceleration of This means the object

If the velocity of an object is zero at one instant, what is true about the acceleration of that object? (There could be more than one correct choice.)

An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion?

Under what condition is average velocity equal to the average of the object's initial and final velocity?

Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be 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 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

Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?

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.)

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

Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct?