Question

A stone of mass 2 kg is falling from rest from the top of a step hill . what will be its kinetic energy after 5 sec ( g = 10 ms-2 )

Answer 1

mass=2kg
initial velocity (u)=0m/s
time (t)=5s
g=10m/s^2

v=u+gt
v=10*5
v=50m/s

Kinetic energy=1/2mv^2
=1/2*2*50*50
=2500 J

Answer= 2500 Joules 

Hope this helps..!!

Answer 2

Given:

Mass of the stone = 2 kg

The initial velocity of the stone (u) = 0

Time = 5 seconds

The value of acceleration due to gravity = 10m/s

To Find:

The kinetic energy of the stone after 5 seconds falls from the rest.

Solution:

The relation between initial velocity, final velocity, time, and acceleration due to gravity is,

⇒ v = u + g t

⇒ v = 0 + 10 × 5 m/s = 50 m/s

The final velocity is 50 m/s.

The kinetic energy of an object = $\frac{1}{2} m v^{2}$

The kinetic energy of the stone = $\frac{1}{2}$× 2 × (50)² = 2500 J

Hence, the kinetic energy of the stone is 2500 Joules.