physics about Mechanics

1.some lorries have a tail-lift loader(貨櫃車後面果個升降板) at the back.The loader flaps to the horizontal when in use.lt functions as a lift for loading and unloading goods.

Suppose some goods of mass of 500kg are put on the platform and to be unloaded.The platform is 1.3m above the groud.

a.When the goods are unloaded at a uniform speed onto the ground, what is the work done on the goods by the platform?

b.suggest another way to unload goods from the lorry .Give one disadvantages of this method.