Question

A ball dropped from a height h from a long multi-storey building. Identify which of the following statements is true?

• A. The potential energy of the ball is conserved
  
• B. The kinetic energy of the ball is conserved
  
• C. The difference between the potential energy and the kinetic energy is a constant as the ball falls.
• D. The sum of the kinetic and potential energies of the ball is a constant
• E. The momentum of the ball is constant as the ball

Answer 1

Answer: (D)

The sum of the kinetic and potential energies of the ball is a constant

Total mechanical energy T.E = K.E + P.E

According to law of conservation of energy, the total mechanical energy of an isolated system is always conserved.

Thus the sum of kinetic energy and potential energy of the ball is constant.