NTA Abhyas JEE Main2020PhysicsWork, Power and EnergyPractice
A particle is projected vertically upwards with a speed of 16 m s - 1 , after some time, when it again passes through the point of projection, its speed is found to be 8 m s - 1 . It is known that the work done by air resistance is the same during upward and downward motion. Then the maximum height attained by the particle is (Take g = 10 m s - 2 ) :
Options
- A8 m
- B4.8 m
- C17.6 m
- D12.8 m
Correct answer
A. 8 m
Step-by-step solution
From work-energy theorem For upward motion 1 2 m 1 6 2 = mgh + W (work by air resistance) For downward motion 1 2 m 8 2 = mgh - W ⇒ 1 2 1 6 2 + 8 2 = 2 gh or h = 8   m