Explain how wedge is used for raising heavy loads. Also give principle of it.
Sol.: Principle of wedge: A wedge is small piece of material having two of their opposite faces not parallel. To lift block of weight W, it is pushed by horizontal force P which lifts the block by imparting reaction on the block in direction 1r to meeting surface that is always greater than total downward force applied by block W This will cause resultant force acting in upward direction on block and moves up.