A chain of length l and mass m lies in a pile on the floor. If its end A is raised vertically at a constant speed v, express in terms of the length y of chain that is off the floor at any given instant (a) the magnitude of the force P applied to A, (b) the reaction of the floor.

Explanation:

mass per unit length = m / l

At the given instant , length of chain in air = y

mass of chain hanging in air = my / l

weight of chain = mgy / l

Let F be the force applied to pull the chain in upward direction

F - weight of chain = mass x acceleration

F - mg y / l  = 0 ( acceleration is zero )

F   =   mg y / l

b ) Reaction of the floor = weight of chain lying on the floor

=  m g - weight of chain in air

= mg - mgy / l

=  mg ( 1 - y / l )

report!

explanation:

physics means: "the branch of science concerned with the nature and properties of matter and energy. the subject matter of physics, distinguished from that of chemistry and biology, includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms."