4. toby glances at the speedometer on his bicycle as he begins to roll downhill. it indicates he is…

4. toby glances at the speedometer on his bicycle as he begins to roll downhill. it indicates he is traveling at 12 miles per hour when he initially looks at it and 20 miles per hour 4 seconds later. his acceleration is: a. 2 mph/sec. b. 3 mph/sec. c. 5 mph/sec. d. 8 mph/sec. 9. if an object is accelerated, all of the following may occur except: a. a change of speed. b. a change of direction. c. it remains motionless. d. a change of direction and speed.

4. toby glances at the speedometer on his bicycle as he begins to roll downhill. it indicates he is traveling at 12 miles per hour when he initially looks at it and 20 miles per hour 4 seconds later. his acceleration is: a. 2 mph/sec. b. 3 mph/sec. c. 5 mph/sec. d. 8 mph/sec. 9. if an object is accelerated, all of the following may occur except: a. a change of speed. b. a change of direction. c. it remains motionless. d. a change of direction and speed.

Answer

Question 4

Explanation:

Step1: Recall the acceleration formula

Acceleration (a=\frac{v - u}{t}), where (v) is final velocity, (u) is initial velocity, and (t) is time.

Step2: Substitute the values

Here, (u = 12) mph, (v=20) mph, (t = 4) sec. Then (a=\frac{20 - 12}{4}) [a=\frac{8}{4}=2] mph/sec

Answer:

a. 2 mph/sec

Question 9

Brief Explanations:

Acceleration is the rate of change of velocity. Velocity is a vector quantity (has both magnitude and direction). If an object is accelerated, its velocity changes. A change in velocity can be a change in speed (magnitude of velocity), a change in direction, or both. If an object remains motionless, its velocity is (v = 0) (constant), so there is no acceleration.

Answer:

c. it remains motionless.