A rock of mass 200kg is dropped from a height of 200m. What is the Kinetic energy at: a) 0 seconds
b) 2 seconds
c) 4 seconds
d) just before it hits the ground

Explanation:

1.

M=200kg

H=200m

for 0 second

now

ke=1/2mv^2

=1/2 .200.200/0

=40000/2

=20000 kgm/ s

2.

for 2second

now

ke=1/2mv^2

=1/2.200.200/2

=40000/4

=10000 kgm/s

3.

for 4second

now

ke= 1/2mv^2

=1/2.200.200/4

=40000/8

=5000 kgm/s