Question

a ball is gently dropped from a height of 20m. If its velocity increases
uniformly at the rate of 10ms, with what velocity will it strike the ground?
after what time will it strike the ground?​

Answer 1

Explanation:

this is the answer to your question

Answer 2

Distance covered by the ball, s = 20 m

Acceleration, a = 10 m/s2

Initial velocity, u = 0 (since the ball was initially at rest)

Final velocity of the ball with which it strikes the ground, v

According to the third equation of motion:

v 2 = u 2 + 2 as

v 2 = 0 + 2 (10) (20)

v = 20 m/s

Concept Note - Choose the equation of motion wisely out of the three, to minimize the number of steps in calculations.

The ball will strike the ground with a velocity 20 m/s.

According to the first equation of motion:

v = u + at

20 = 0 + 10 (t)

t = 2s

Hence, the ball will strike the ground after 2s with a velocity of 20 m/s.