Question

To drive a nail into a wooden block, we blow a hammer on the nail. When a ball hits a wall, it bounces back In both of these examples, a large force acts for a very short duration producing a finite change in the momentum of the body. Here it is difficult to measure force and time separately. The product of the force and time that produces a finite change of momentum is called impulse. Impulse = Force x time duration = Total change in momentum. SI unit of impulse is Ns or kgm/s. It is a vector quantity having the direction same as that of force or the change in momentum. A large force acting force a short time is called an impulsive force. For a variable force, impulse J is given by J = P2 - P1 = ∫dp = ∫Fdt = Area under the force-time curve.

A body of mass m is moving with an acceleration 'a' under the action of a force 'g/4'. The weight of the body is

Force produces an acceleration of a₁ in a body and the same force produces an acceleration of a₂ which is twice to a₁ in another body. If the two bodies are combined and the same force is applied on the combination, the acceleration produced in it is

An object of mass 5 kg is attached to the hook of a spring balance and the balance is suspended vertically from the roof of a lift. The reading on the spring balance, when the lift is going up with an acceleration of 0.25 ms⁻² (g= 10m/s⁻²)