What kinetic energy does the sack have just before it strikes the floor?

-a 98.0 n sack of grain is hoisted to a storage room 50.0 m above the ground floor of a grain elevator. the rope being used to lift the sack of grain breaks just as the sack reaches the storage room.

When an object is at any height above the ground, it has gravitational potential energy. If the object falls, it loses this gravitational potential energy and this energy is converted to kinetic energy. By this logic, we can say:

Gravitational potential energy of grain sack = Kinetic energy of grain sack

GPE = mgh
        = (mg) x h
        = 98.0 x 50.0
        = 4,900 J

You can find results and justify them? you can test your hypothesis