E1T3 Retake PreAP 2016

1. What is the speed of an object at rest?

A. 0.0 m/s

B. 1.0 m/s

C. 9.8 m/s

D. 9.81 m/s

The speed of an object at rest is 0.0 m/s because when an object is at rest, it is not moving and therefore has no speed or velocity. Speed is defined as the distance traveled per unit of time, and if there is no distance traveled, the speed is zero. In this case, since the object is at rest, it is not moving and its speed is 0.0 m/s.

Explanation

The speed of an object at rest is 0.0 m/s because when an object is at rest, it is not moving and therefore has no speed or velocity. Speed is defined as the distance traveled per unit of time, and if there is no distance traveled, the speed is zero. In this case, since the object is at rest, it is not moving and its speed is 0.0 m/s.

2. Which of the following situations represents a negative displacement? (Assume positive position is measured vertically upward along a y-axis.)

A. A cat stands on a tree limb.

B. A cat jumps from the ground onto a tree limb.

C. A cat jumps from a lower tree limb to a higher one.

D. A cat jumps from a tree limb to the ground.

In this scenario, the cat is moving downwards from a higher position (tree limb) to a lower position (ground). Since the positive position is measured vertically upward along the y-axis, any movement in the opposite direction (downward) represents a negative displacement. Therefore, option d is the correct answer as it represents a negative displacement.

Explanation

In this scenario, the cat is moving downwards from a higher position (tree limb) to a lower position (ground). Since the positive position is measured vertically upward along the y-axis, any movement in the opposite direction (downward) represents a negative displacement. Therefore, option d is the correct answer as it represents a negative displacement.

3. A toy car rolls from +3 m to +5 m. Which of the following statements is true?

A. xf = +3 m

B. xi = +3 m

C. delta x = +3 m

D. vavg = 3 m/s

The correct answer is b. xi = +3 m. This statement is true because xi represents the initial position of the toy car, and in this case, it starts at +3 m.

Explanation

The correct answer is b. xi = +3 m. This statement is true because xi represents the initial position of the toy car, and in this case, it starts at +3 m.

4. What is the correct description of any change of position farther to the left of zero?

A. positive displacement

B. negative distance

C. positive position

D. negative displacement

A change of position farther to the left of zero indicates that the object has moved in the negative direction, or to the left. Displacement refers to the change in position, and since the object has moved to the left, the displacement is negative. Therefore, the correct answer is d. negative displacement.

Explanation

A change of position farther to the left of zero indicates that the object has moved in the negative direction, or to the left. Displacement refers to the change in position, and since the object has moved to the left, the displacement is negative. Therefore, the correct answer is d. negative displacement.

5. Rank in increasing order the distances traveled by objects having the following pairs of average velocity and time of motion.I. v_avg = -4.0 m/s, t = 2.0 sII. v_avg = +3.0 m/s, t = 2.0 sIII. v_avg = -3.0 m/s, t = 3.0 s

A. III, I, II

B. II, III, I

C. II, I, III

D. III, II, I

The distance traveled by an object can be calculated by multiplying the average velocity by the time of motion. In this case, for option II, the average velocity is +3.0 m/s and the time of motion is 2.0 s, resulting in a positive distance traveled. For option I, the average velocity is -4.0 m/s and the time of motion is 2.0 s, resulting in a negative distance traveled. For option III, the average velocity is -3.0 m/s and the time of motion is 3.0 s, resulting in a negative distance traveled. Therefore, the correct order of distances traveled in increasing order is II, I, III.

Explanation

The distance traveled by an object can be calculated by multiplying the average velocity by the time of motion. In this case, for option II, the average velocity is +3.0 m/s and the time of motion is 2.0 s, resulting in a positive distance traveled. For option I, the average velocity is -4.0 m/s and the time of motion is 2.0 s, resulting in a negative distance traveled. For option III, the average velocity is -3.0 m/s and the time of motion is 3.0 s, resulting in a negative distance traveled. Therefore, the correct order of distances traveled in increasing order is II, I, III.

E1t3 Retake Preap 2016