Name the class to which the following levers belong :

(a) A pair of scissors,

(b) a lemon squeezer,

(c) a nut cracker,

(d) a pair of sugar tongs,

(e) a beam balance,

(f) an oar rowing a boat,

(g) a wheel barrow,

(h) a see-saw,

(i) a pair of pliers,

(j) a crowbar.

The diagram given below shows the three kinds of levers. Name the class of each lever and give one example of each class.

(a)

(b)

(c)

How does the friction at the fulcrum affect the mechanical advantage of a lever ?

State three differences between the three classes of levers.