Fill in the blanks.

(a) The ratio of the load lifted by a machine to the effort applied on it is called …………… .

(b) Work done on an object is the product of …………… and …………… .

(c) There are three types of levers based on the positions of ……………, …………… and …………… .

(d) The ratio of work done by a machine to the work done on the machine is termed as …………… of the machine.

(e) The arrangement of several pulleys to pick heavy loads is called …………… .

State whether the following statements are true or false. Correct the false statements.

(a) A girl riding a bicycle is getting zero work done.

(b) When the value of mechanical advantage is equal to one, it means that effort is equal to load.

(c) In class III lever, the fulcrum is between the load and the effort.

(d) In a fixed pulley, the pulley can move.

(e) Tyres of cars and buses are examples of wheel and axle.

What is the formula to find out the mechanical advantage in a lever?

1. $\dfrac {\text {Effort}}{\text {Load}}\\[1em]$
2. $\dfrac {\text {Load arm}}{\text {Effort arm}}\\[1em]$
3. $\dfrac {\text {Effort arm}}{\text {Load arm}}\\[1em]$
4. $\dfrac{\text {Length}}{\text {Height}}$

What type of simple machine is a bottle opener?

1. Wedge
2. Class I lever
3. Class II lever
4. Wheel and axle