If an automobile engine is overheated, it is cooled by putting water on it. It is advised that the water should be put slowly with engine running. Explain the reason.

A very hot glass on putting in cold water cracks. What does this change indicate?

While watering a distant plant, a gardener partially closes the exit hole of the pipe by putting his finger on it. Explain why this results in the water stream going to a larger distance.

A steam engine boiler is maintained at 250^(@)C and water is converted into steam. This steam is used to do work and heat is ejected to the surrounding air at temperature 300K. Calculate the maximum efficiency it can have?

Indian style of cooling drinking water is to keep it in a pitcher having porous walls. Water comes to the outer surface very slowly and evaporates .Most of the energy needed for evaporation is taken from the water itself and the water is cooled down. Assume that a pitcher contains 10kg water and 0.2g of water comes out per second. Assuming no backward heat transfer from the atmosphere to the water, calculate the time in which the temperature decreases by 5^(@)C . Specific heat capacity of water = 4200J kg^(-1).^@C^(-1) and latent heat of vaporization of water = 2.27 xx 10^(6)J kg^(-1)

The force of resistance encountered by water on a motor boat of mass m going in still water with velocity v is proportional to the velocity vdot At t=0 when its velocity is v_0, then engine shuts off. Find an expression for the position of motor boat at time t and also the distance travelled by the boat before it comes to rest. Take the proportionality constant as k > 0.

Assertion : Through the use of catalytic converters, unburnt hydrocarbons are changed into carbon monoxide which in turn is changed into nitrogen oxides and water. Reason : Motor vehicles equipped with catalytic converters should use leaded petrol to protect the catalyst from degradation.

The power out put of an automobile engine is advertised to be 200 ap at 6000rpm. What is the corresponding torque?

A person's skin is more selveely burnet when put in contact with 1g of steam at 100^(@) then when put inn contact with 1g of water at 100^(@) Explain