A bullet emerges from a barrel of length 1.2 m with a speed of 640 ms^{$$-$$1}. Assuming constant acceleration, the approximate time that it spends in the barrel after the gun is fired is

A body of mass 2 kg moves in a horizontal circular path of radius 5 m. At an instant, its speed is 2$$\sqrt5$$ m/s and is increasing at the rate of 3 m/s$$^2$$. The magnitude of force acting on the body at that instant is,

If a string, suspended from the ceiling is given a downward force F_{1}, its length becomes L_{1}. Its length is L_{2}, if the downward force is F_{2}. What is its actual length?

A golf ball of mass 50 gm placed on a tee, is struck by a golf-club. The speed of the golf ball as it leaves the tee is 100 m/s, the time of contact on the ball is 0.02 s. If the force decreases to zero linearly with time, then the force at the beginning of the contact is