Question

a. a body of mass 5 kg is rest at height of 20 m above the ground. calculate its potential energy at that height and its kinetic energy just before hitting the ground.

b. a body of mass 5 kg moves vertically up with a velocity of 10 m/s the ground.
calculate its kinetic energy and the maximum height attained

Answer 1

a.potential energy=mgh=5×9.8×20=980
kinetic energy =1/2mv^2
v=gt
v=9.8
as the velocity at 1st second and last second is equal
ke=1/2×5×100
250
b.h=1/2gt^2
g=v/t
10=10/t
so t=1
h=1/2×10
h=5
ke =1/2mv^2
1/2×5×100
250