Question

A stone of mass 2kg is dropped from the top of a hill. It takes 5 sec to reach the ground
Find the kinetic Energy. ?
(Take G= 10m/s)​

Answer 1

Given:

mass (m)= 2kg

time(t)= 5s

g= 10 m/s2

let the velocity = v

thus, speed = distance/ time => distance = speed * time

here, distance = height (h) => h= v*5= 5v

Kinetic Energy (K.E) =1/2 (m * v2)

=> 1/2 ( 2 * v2)

=> v2

Potential Energy(P.E) = mgh

=> 2 * 10* h = 2* 10 * 5v

=> 100v

According to law of conservation of energy the total mechanical energy of a body remains same throughout its activity.

Therefore,

P.E=K.E

v2 = 100v

v= 100 m/s

this

Kinetic energy = v2 = (100)^2= 10000J