NEET2017PhysicsWork, Power and EnergyActual
Consider a drop of rain water having mass 1   g falling from a height of 1   km . It hits the ground with a speed of 50   m   s - 1 . Take g constant with a value 10  m   s - 2 . The work done by the (i) gravitational force and the (ii) resistive force of air is
Options
- Ai - 10 J i i - 8.25 J
- Bi 1.25 J i i - 8.25 J
- Ci 100 J i i 8.75 J
- Di 10 J i i - 8.75 J
Correct answer
D. i 10 J i i - 8.75 J
Step-by-step solution
By Work-Energy Theorem W g + W a = K f - K i m g h + W a = 1 2 m v 2 - 0 10 - 3 × 10 × 10 3 + w a = 1 2 × 10 - 3 × 50 2 W a = - 8.75 J work done due to gravity = mgh = 10 − 3 × 10 × 10 3 = 10 J