Question

A body of mass 5 kg which was initially at a height of 100 m from the surface of earth starts falling freely. The kinetic energy of the body when it will be a height of 50 m
from surface of earth-(g= 10 m/s^2)
a) 250 J
b) 2500 J
c) 2000 J
d) 750 J​

Answer 1

The correct option is : b) 2500 J

The total potential energy(PE) when it is at height(H) 100 m from surface

Mass(m) = 5 kg

PE = mgH

PE = 5 x 10 x 100

PE = 5000 J

when the body is at 50 m

Total energy (TE) = potential energy (PE) + kinetic energy (KE)

⇒ 5000 = mgH + KE

⇒ KE = 5000 - ( 5 x 10 x 50 )

⇒ KE = 5000 - 2500

    ∴ KE = 2500 J

HOPE THIS HELPS YOU !!   : )