NTA Abhyas JEE Main2020PhysicsLaws of MotionPractice
A small spherical ball (obeying Stoke's law for viscous force) is thrown up vertically with a speed 20 m s - 1 and is received back by the thrower at the point of projection with a speed 10 m s - 1 . Neglecting the buoyant force on the ball, assuming the speed of the ball during its flight to be never equal to its terminal speed and taking the acceleration due to gravity g = 10 m s - 2 , find the time of flight of th
Correct answer
3
Step-by-step solution
m g → + k v → = md v → dt g →   dt + k m   v →   dt = d   v → Integrating both sides ∫ 0 T g → dt + k m ∫ 0 T v → dt = ∫ u → v → d v → g → T + 0 = v → - u → gT = v - - u = v + u ⇒ T = v + u g = 3   s