The force which opposes one surface moving over another is

The percentage of the energy supplied to a device is called

The force acting on unit area is called

At equilibrium, there is

Food and fuels like oil, gas, coal etc are concentrated stores of

A mixture of methane and carbon dioxide gas is

In a body, the whole mass is concentrated at a point called

The energy which can not be replaced when once used up is called

The energy possessed by a body by virtue of its motion is called

A quantity which has only magnitude is