# Door bounces ?

1. Feb 21, 2004

### AnthreX

when you close those sliding doors really hard
the door will eventually bounce back out about half way where you have pushed the door. is it because every force has an opposite side of force ? for example when we put the book on the table,
the gravity force is pulling the book down but the table is actually pushing the book upwards which makes it even, so the book stays on the very still.

2. Feb 22, 2004

### LURCH

Yes, you are seeing a reaction to the original force put into the door. The specific mechanism by which this law is manifesting tiself is elasticity. When the door htis the doorframe, both are slightly deformed by the force of the impact. As they are being forced out of their original shape, both objects store the energy originally put into them by your arm, this energy building up as potential energy in the material being deformed. When the material's resistence to deformation is equal to the amount the remaining force acting against it, the door and frame both come to a stop, with all that energy stored in the material. Then, the material's tendency to return to its original shape releases the stored potential energy in the act of "springing back" into shape. This energy pushes the door back away from the doorframe, just as the original deforming force pushed it into the doorframe.

3. Feb 22, 2004

### AnthreX

wow

r u a teacher ?

damn nice explaination