A chain of length L,mass M kept vertical so it just touches ground.A height x of it from bottom falls down.Find the total force exerted by it on ground.
1Its a Simple sum
SInce a Hieght of x Falls therefore the vel of the remaining part can be easily found by w.e. energy theorem as gravity is the only force acting on it.
and at that time we use the concept that
Mdv/Dt=Fext +vreldm/dt (rocket concept)
now take the mass that hass fallen
dv/dt=0 thereofre
Fext=Vreldm/dt
therefore from there i think u can find the answer
1How can you use that concept here? The mass (part of the chain) doesnot get detached from the chain.
The whole chain starts falling down and we have to find the force exerted when 'x' length falls completely on the ground. This is how I interpret. Correct me if I am wrong. There is no meaning of a part of chain getting detached (chains are not meant for that [3] )
1http://www.targetiit.com/iit-jee-forum/posts/chain-and-variable-mass-13892.html