Question

A BALL IS DROPED FROM A HEIGHT H. WHEN IT REACHES THE GROUND , ITS VELOCITY IS 40 M/S FIND THE HEIGHT H

Answer 1

Answer:

Velocity gained after falling a height equal to h

1

=100m is V

1

=

2gh

1

=

20×100

=10

2

m/s

so velocity with which it will rebound will be V

2

=e×V

1

, where e is the restitution coefficient.

so V

2

=0.2×10

2

=2

2

m/s

the new height reached will be h

2

=

2g

V

2

2

=

20

8

=0.4m

Answer 2

Since the ball was dropped from some height therefore we have,

u=0 m/s

v=40m/s

let, g=10m/s^2

t=?

h=?

we know,

v=u+gt

Putting the values we get,

40=0+10*t

40=10t

t=40/10

t=4 sec

Since, h=ut+1/2gt^2

Pitting the values

h=0*4+1/2*10*4*4

h=80 m

Hope that satisfies