JEE Main20199 Jan 2019Morning ShiftPhysicsWork, Power and EnergyActual
A block of mass m , lying on a smooth horizontal surface, is attached to a spring (of negligible mass) of spring constant k . The other end of the spring is fixed, as shown in the figure. The block is initially at rest in its equilibrium position. If now the block is pulled with a constant force F , the maximum speed of the block is:
Options
- AF m k
- B2 F m k
- Cπ F m k
- DF π m k
Correct answer
A. F m k
Step-by-step solution
When block attains maximum speed net force on m is zero. ∴ F = k x Or x = F k From work energy theorem - 1 2   k   F k 2 + F F k = 1 2 m V m a x 2 F 2 2 k = 1 2 m V m a x 2 V m a x = F k m