If velocity become double. Then temperature become 4 time?

No, the relationship between velocity and temperature is not directly proportional in this way. Doubling the velocity of an object does not necessarily mean that the temperature will become four times higher. Temperature is a measure of the average kinetic energy of the particles in a substance, while velocity is a measure of the speed of an object in a particular direction. The relationship between velocity and temperature is more complex and depends on various factors such as the specific heat capacity of the substance and the type of energy transfer involved.

Yes, if the velocity of a gas becomes double, its temperature will become four times the original temperature. This is because the average kinetic energy of the gas molecules is proportional to the square of their velocity. So, if the velocity doubles, the kinetic energy will increase by a factor of four. The temperature is proportional to the average kinetic energy, so it will also increase by a factor of four.