Question

A ball starts at the origin from rest rolling down a hill. It takes seven seconds for the ball to reach point “A”, which is 25 meters from the origin. At point “B”, the ball’s velocity is 15 m/s. You may assume constant acceleration.

a. What is the acceleration of the ball? [2]
b. What is the velocity of the ball at point “A”? [2]
c. What is the distance between points “A” and “B”? [2]
d. SKETCH the corresponding velocity-time graph for the ball between the origin and point “B” [1]

Answer 1

a. OA = 0.5a*t^2 = 25 m.
0.5a*7^2 = 25
0.5a*49 = 25
a = 1.02 m/s^2

b. V = a*t = 1.02 * 7 = 7.14 m/s.

c. AB = (V^2-Vo^2)/2a
AB = (15^2-7.14^2)/2.04 = 85.3 m.

Answer 2

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