Question

A ball has been dropped from a height, then for this situation mark out the correct statement(s)

• A. PE of the ball is decreasing.
• B. Work done by gravity force is positive.
• C. KE of the ball increases.
• D. Work done by gravity force is negative.

Answer 1

Answer: (A), (B), (C)

KE of the ball increases.

1. Potential energy is given by, $$\begin{gathered} P.E=mgh \\ wheremismass,gisgravitationalacceleration,hisheightofbody \end{gathered}$$
2. Kinetic energy is given by, $$\begin{gathered} K.E=\frac{1}{2}m{v}^2 \\ wherevisvelocityofbody \end{gathered}$$
3. Work done, $$\begin{gathered} W=Fx=mgx \\ wherexisdisplacement \end{gathered}$$
4. When the ball is dropped from some height, the potential energy of a ball decreases as the height decreases. Potential energy depends on the height of an object.
5. While falling down the velocity of the ball gets increased and kinetic energy is directly proportional to the square of the velocity. Hence kinetic energy of a ball increases.
6. Gravitational acceleration always acts in the downward direction. As the direction of the ball is downward, the work done by gravity is positive.

Option (a), (b) and (c) are correct options.