This is a well-known phenomenon, and a proper explanation is needed. It seems counter-intuitive since common materials expand upon heating due to faster oscillation of atoms. There would be some reasoning to this observation with rubber that goes in opposite direction.
[Physics] Why does rubber shrink when it is heated
everyday-lifethermodynamics
Related Solutions
When the player hits the ball with top spin, it makes the ball, well, spin.
By spinning, the ball will modify the airflow around itself and thus create an air pressure profile which will deflect the ball : this is the Magnus effect.
So by applying top spin on the ball the way tennis players do, the ball is rotating in the direction of the trajectory. This will bend the trajectory downwards. If you look at the ball's speed as a vector, the vertical component of the top-spun ball's velocity is greater than the normal served ball.
You simply direct the ball more vertically into the ground with a top spin. So after contact with the ground, the ball with top spin will leave the ground more vertically than a normal ball.
Since you are familiar with the sport, you might also have noticed that after contact, the top-spun ball will slightly accelerate towards you. This comes from the fact that part of its rotation has transfered itself into horizontal momentum. If you let a spinning ball fall vertically on the ground, after contact, it will fly out flat in some direction. I think this is also one of the reason why top spin serves are so hard to handle.
In an ideal gas
where P is the absolute pressure of the gas, V is the volume of the gas, n is the amount of substance of gas (measured in moles), T is the absolute temperature of the gas and R is the ideal, or universal, gas constant.
The capped gas in the bottle cools coming to a thermodynamic equilibrium , through conduction to the walls, and also according to the black body radiation # law everything cools at a certain rate. In the formula above the combined pressure times volume has to become smaller. If the walls are not rigid the imbalance of the inside pressure to the outside compresses the wall until pressure equilibrium is reached. The same is true if you put a capped half empty bottle in the freezer. - - - - - - -
#it has been pointed out in a comment air does not follow the black body radiation formula well , it has small emissivity and conduction has to be the main cooling mechanism.
Best Answer
Here is Feynman's intuitive explanation: rubber contains very long molecules like chains. nearby atoms continuously hit this chains. of course you can imagine the stronger hitting be, the shorter will be chain. now heating rubber makes atoms faster, make them hit stronger which makes chains and so rubber shorter.