Why are musical instruments first warmed up before performing?

Why are musical instruments first warmed up before performing?
Ans: When musical instruments are used for performance, either pipe type or string type or the layers type, they are in motion or are exposed to slightly high temperature of exhaled air or hand or anything else. The frequency of music generated corresponds to that temperature.
When the device is first used after a long period of rest or abstinence, the temperature of the device will be equal to that of the environment, i.e. colder than the performing temperature. So, this will decrease the velocity of sound as well as the frequency produced. Such phenomenon is defined as the device going ‘flat’.
In order to prevent this, they should be warmed up for few minutes, bringing the temperature to the performing level and then brought to use.