A body of mass 100 kg falls from a height of 10 m. Its increase in kinetic energy is :
Answer & explanation
Correct answer: option 3
Potential energy at the initial position = mgh = 10 x 9.8 x 10 = 980 J
Let the final velocity of the body just before it touches the ground be v.
\(v^2 = u^2 + 2gh\)
\(v^2 = 0+ 2*9.8*10 = 196 \text{ m}^2/s^2\)
∴ Kinetic energy of the body just before it touches ground = \(\frac{1}{2}mv^2\)
= \(\frac{1}{2}*10*196 = 980 \text{ J}\)
Hence, kinetic energy gained =initial potential energy.