NTA Abhyas JEE Main2020PhysicsWork, Power and EnergyPractice
Consider an elliptically shaped rail PQ in the vertical plane with O P = 3 m and O Q = 4 m . A block of mass 1 kg is pulled along the rail from P to Q with a force of 18 N , which is always parallel to line PQ (see the figure given). Assuming no frictional losses, the kinetic energy of the block when it reaches Q is ( n × 10 ) joules. The value of n is (take acceleration due to gravity = 10 m s – 2 )
Correct answer
5
Step-by-step solution
Using work-energy theorem W m g + W F = Δ K E - m g h + F d = Δ K E - 1 × 10 × 4 + 18 5 = Δ K E Δ K E = 50 ∴       n = 5