What do you mean by the mechanical advantage of a lever ?

Which class of lever has the mechanical advantage always more than 1 ? Give an example.

Give one example of class I lever in each case where the mechanical advantage is

(i) more than 1

(ii) equal to 1

(iii) less than 1.

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.