NEET2004PhysicsWork, Power and EnergyActual
A stone is tied to a string of length ' l ' and is whirled in a vertical circle with the other end of the string as the centre. At a certain instant of time, the stone is at its lowest position and has a speed ' u '. The magnitude of change in velocity as it reaches a position where the string is horizontal ( g being acceleration due to gravity)is:
Options
- A2 (u^2-g l )
- Bu^2-g l
- Cu- u^2-2 g l
- D2 g l
Correct answer
A. 2 (u^2-g l )
Step-by-step solution
According to the question Total energy at A = Total energy at B array l 1 2 m u^2 = 1 2 m v^2+m g l v^2 = u^2-2 g l array Change in magnitude of velocity = u^2+v^2 = 2 (u^2-g l )