Physics 2014 JAMB Past Questions - Question 12: An object of mass 20kg is released from a height of 10m above the ground level .The kinetic energy of the object just before it hits the ground is

Correct Answer

B

Explanation

From the principle of conservation of mechanical energy; The kinetic energy (ke) of the object just before hitting the ground = the potential energy (Pe.) at the maximum height ke = Pe.= mgh = 20x10x10 = 2000J
To find the kinetic energy of the object just before it hits the ground, we can use the principle of conservation of energy. The potential energy of the object at the initial height is given by the formula:

Potential Energy = mass * gravitational acceleration * height

In this case, the mass of the object is 20 kg, the gravitational acceleration is approximately 9.8 m/s^2, and the height is 10 m. Therefore, the potential energy at the initial height is:

Potential Energy = 20 kg * 9.8 m/s^2 * 10 m = 1960 Joules

According to the conservation of energy, this potential energy is converted entirely into kinetic energy just before the object hits the ground. Therefore, the kinetic energy of the object just before it hits the ground is also 1960 Joules.