The figure below shows a wheel barrow of mass 15 kg carrying a load of 30 kgf with its centre of gravity at A. The points B and C are the centre of wheel and tip of the handle such that the horizontal distance AB = 20 cm and AC = 40 cm.

Find:

(a) the load arm,

(b) the effort arm,

(c) the mechanical advantage, and

(d) the minimum effort required to keep the leg just off the ground.

A lever of length 9 cm has its load arm 5 cm long and the effort arm is 9 cm long.

(a) To which class does it belong?

(b) Draw diagram of the lever showing the position of fulcrum F and directions of both the load L and effort E.

(c) What is the mechanical advantage and velocity ratio if the efficiency is 100%?

(d) What will be the mechanical advantage and velocity ratio if the efficiency becomes 50%?

The diagram below shows a lever in use.

(a) To which class of lever does it belong?

(b) Without changing the dimensions of the lever, if the load is shifted towards the fulcrum what happens to the mechanical advantage of the lever?

A fire tongs has its arms 20 cm long. It is used to lift a coal of weight 1.5 kgf by applying an effort at a distance 15 cm from the fulcrum.

Find:

(i) the mechanical advantage of fire tongs and

(ii) the effort needed.