Question

A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of

10m s -2 , with what velocity will it strike the ground? After what time will it strike the Ground?

Answer 1

The ball strikes the ground at 20 m/s after 2 seconds

Step-by-step explanation:

Free Fall Motion

Any object that is being acted upon only by the force of gravity is said to be in a state of free fall.

If an object is dropped from rest in a free-falling motion, it falls with a constant acceleration called the acceleration of gravity, which value is assumed as
`g = 10 m/s^2`.

The final velocity of a free-falling object after a time t is given by:

vf=g.t

The distance traveled by a dropped object is:

`\displaystyle y=(gt^2)/(2)`

If we know the height h from which the object was dropped, we can find the time it takes fo hit the ground:

`\displaystyle t=\sqrt{(2h)/(g)}`

The ball is dropped from a height of h=20 m. The time taken to strike the ground is:

`\displaystyle t=\sqrt{(2*20)/(10)}`

t = 2 s

The velocity at which the ball strikes the ground is:

vf = 10 * 2

vf = 20 m/s

The ball strikes the ground at 20 m/s after 2 seconds