The needle is placed, gently on the water surface, surface tension of water makes it to float.

The molecules must have enough kinetic energy is break away from attractive (cohesive) forces between them. The molecules must have enough energy to push back the atmosphere as they escape.

Blowing air increases the rate of evaporation. The latent heat of vaporization required is taken from the spirit, this cause cooling.

Moment = fx, moment can be increased by applying the force at a greater distance from the turning point

The flask is made of double walls that is silvered to reflect back the heat.

The spring get permanent stretch equal to OA

(i). Gravitational force.

(ii). Towards the centre of the earth.

(iii). Reduces, since centripetal force depends on speed radius and mass of the body, but speed and radius is constant.

The paper lifts. the pressure above is lower than pressing below due to increased velocity

To stop the mercury form returning to the bulb after it is removed from a body.