Question

a body of mass 2 kg is thrown vertically upward with initial velocity of 2 metre per second what will be its potential energy at the end of 2 second assume gravity equal to 10 metre per second square ​

Answer 1

Initial velocity (u) = 2ms-1
Time = 2s
Acceleration due to gravity = 10ms-2

Therefore displacement of the object after 2 s =

Applying s=ut + 1/2at2 in upward direction

S= 2x2 - 1/2 x 10 x 2x2
S = -16m

Therefore displacement of object is 16m downwards.

Gravitational potential energy = mass x gravitational acceleration x height

Assuming initial gravitational potential energy to be zero,

E = 2kg x 10 x -16m

E = -320J

E is negative because object has moved down causing it to loose gravitational potential energy.