Question 1

An object thrown downward does not experience free fall.

Accepted Answer

An object thrown downward does experience free fall, as long as the only force acting on it is gravity. Free fall is the motion of an object under the sole influence of gravity, regardless of the direction of the motion.

Question 2

A stone is thrown straight up. What is its acceleration at the highest point?

Accepted Answer

9.8 m/s² downward

Question 3

Which statement is correct about the relationship between the average speed and the magnitude of the average velocity for any motion?

Accepted Answer

The average speed is the total distance traveled divided by time, while the magnitude of the average velocity is the total displacement divided by time. Since distance is always greater than or equal to displacement, the average speed is always greater than or equal to the magnitude of the average velocity.

Question 4

Two cars are traveling at the same speed and hit the brakes at the same time. One car has double the deceleration of the other. By what factor does the time required to stop that car compare with that for the other car?

Accepted Answer

The answer of Two cars are traveling at the same...

Question 5

A stone is thrown straight up. What is its acceleration on the way down?

Accepted Answer

The answer of A stone is thrown straight up. What...

Question 6

Which statement below about the distance between the starting and ending positions and the displacement between the starting and ending positions is correct?

Accepted Answer

The distance between the starting and ending positions is the total length of the path traveled, regardless of the direction. The displacement between the starting and ending positions is the straight-line distance between the two points, regardless of the path taken. Therefore, the distance between the starting and ending positions can be greater than, equal to, or less than the magnitude of the displacement between the starting and ending positions. However, the distance between the starting and ending positions is never twice the magnitude of the displacement between the starting and ending positions.

Question 7

Car A is traveling at twice the speed of car B. They both hit the brakes at the same time and undergo identical decelerations. How does the time required for car A to stop compare with that for car B?

Accepted Answer

The answer of Car A is traveling at twice the...

Question 8

A stone is thrown straight up. What is its acceleration on the way up?

Accepted Answer

The answer of A stone is thrown straight up. What...

Question 9

An object thrown upward experiences free fall.

Accepted Answer

Any object thrown upward experiences free fall once it reaches the highest point of its trajectory and starts to come back down. During free fall, the only force acting on the object is gravity, causing it to accelerate downward at a constant rate.

Question 10

When the velocity and acceleration of an object have the same sign, the speed of the object increases.

Accepted Answer

When the velocity and acceleration have the same sign, it means that they are both in the same direction. This causes the object to speed up or increase in velocity, hence the statement is true.

Question 11

An object is in free fall as soon as it is released, whether it is dropped from rest, thrown downward, or thrown upward.

Accepted Answer

Free fall refers to the motion of an object under the sole influence of gravity, without any other forces acting on it. As soon as an object is released, it is under the influence of gravity and thus in free fall. This is true whether the object is dropped from rest, thrown downward, or thrown upward.

Question 12

Two cars are traveling at the same speed and hit the brakes at the same time. One car has double the deceleration of the other. By what factor does the distance required to stop that car compare with that for the other car?

Accepted Answer

The answer of Two cars are traveling at the same...

Question 13

It is possible to have a zero acceleration, and still be moving.

Accepted Answer

If an object is moving at a constant speed in a straight line, it has zero acceleration, but it is still moving. This is because acceleration involves a change in velocity, which can include changes in speed, direction, or both. If there is no change in velocity, there is no acceleration, even if the object is in motion.

Question 14

When the velocity and acceleration of an object have opposite signs, the speed of the object increases.

Accepted Answer

When the velocity and acceleration of an object have opposite signs, the speed of the object decreases. This is because the acceleration is acting against the direction of motion, slowing down the object. When they have the same sign, the speed increases.

Question 15

Free fall is the motion of an object subject only to the influence of gravity.

Accepted Answer

Free fall only involves the force of gravity acting on the object and no other external forces.

Question 16

The average velocity of a car traveling with a constant acceleration during a certain time interval is equal to the mean of the velocities at the beginning and end of that time interval.

Accepted Answer

For constant acceleration, the average velocity is the arithmetic mean of the initial and final velocities.

Question 17

The slope of a line connecting two points on a position versus time graph gives

Accepted Answer

The slope of a line connecting two points on a position versus time graph represents the average velocity, as it shows the change in position over the change in time between those two points.

Question 18

You drive 6.00 km at 50.0 km/h and then another 6.00 km at 90.0 km/h. Your average speed over the 12.0 km drive will be

Accepted Answer

To find the average speed, we need to divide the total distance by the total time.

Total distance = 6.00 km + 6.00 km = 12.00 km

Total time = (6.00 km / 50.0 km/h) + (6.00 km / 90.0 km/h)

Total time = 0.12 h + 0.067 h = 0.187 h

Average speed = Total distance / Total time = 12.00 km / 0.187 h = 64.17 km/h

Since the average speed is less than 70.0 km/h, the answer is C.

Question 19

Suppose that an object travels from one point in space to another. Make a comparison between the displacement and the distance traveled.

Accepted Answer

The displacement is the straight-line distance between the starting and ending points of an object's motion. It is the shortest distance between the two points. On the other hand, the distance traveled is the actual path length taken by the object to move from the starting point to the ending point, which can be greater than or equal to the displacement depending on the path taken. Therefore, the displacement can be no greater than the distance traveled but can be equal to it if the object moves in a straight line, and it can be less than the distance traveled if the object moves along a curved path. Hence, the best choice is (C).

Question 20

Car A is traveling at twice the speed of car B. They both hit the brakes at the same time and undergo identical decelerations. How does the distance required for car A to stop compare with that for car B?

Accepted Answer