Question

spring fitted doors close by themselves when released you want to keep the door open for a long time say for an hour if you put a half kg stone in front of the front door It does not help the change slides with the door and the door gets closed however if you sandwich a 20 gram piece of wood in the small gap between the door and the floor the door stays open explain why a much lighter piece of wood is able to keep the door open while the heavy stone fails​

Answer 1

Answer:

spring fitted doors close by themselves when released you want to keep the door open for a long time say for an hour if you put a half kg stone in front of the front door It does not help the change slides with the door and the door gets closed however if you sandwich a 20 gram piece of wood in the small gap between the door and the floor the door stays open explain why a much lighter piece of wood is able to keep the door open while the heavy stone fails

Answer 2

simple - the force the potential or you can say kinetic energy of the spring is higher than the half kg stone , also  the friction does not help in the slippery floor. But the 20 gms piece of wood is using friction to its fullest. but however , sometimes even the piece of wood fails...................