Question

a body of mass 12.0kg is placed on an orange tree 13m above the ground. .....1. calculate the potential energy .......2. if the body is released from this height what will be the kinetic energy just before it hits the ground.(g = 10 m/s)​

Answer 1

Given , mass = 12.0kg

height = 13m

acceleration due to gravity = 10m/s

1.ans

Potential energy = mass×acceleration due to gravity×height

Potential energy = 12kg×10m/s×13m

Potential energy = 1,560J

2.ans

Remember this when a body is above the ground potential energy is equal to kinetic energy.

Potential energy = kinetic energy

kinetic energy = ½× mass×(velocity)²

1560J = ½×12kg×v²

1560J = 6kg× v²

1560kgms-2 - 6kg = v²

v² = 1,554m/s²

K.E = ½×m×v²

K.E =( ½)(12kg)(1,554m/s²)

K.E = 9,324J