A ball is gently dropped from a height of 20 m. If its velocity
increases uniformly at the rate of 10 m s2, with what velocity
will it strike the ground? After what time will it strike the
ground?
Answers
Answer:
Velocity = 20 m/s
Time = 2 seconds
Explanation:
u = 0 (Initial Velocity)
a = 10 m/s² (Acceleration)
s = 20 m (Distance)
(a)
v = ? (Final Velocity)
By The third equation of motion
v² = u² + 2as
= 0 + 2 X 10 X 20
v² = 400
v = 20 m/s
Therefore, Velocity with which it will hit the ground is 20 m/s.
(b)
t = ? (Time)
By second equation of motion
s = ut +1/2 at²
20 = 0 X t + 1/2(10 X t²)
20 = 1/2(10 X t²)
40 = 10 X t²
t² = 4
t = 2 sec
Therefore, Total time taken by the ball to hit the ground is 2 seconds.