Define the terms mechanical advantage, velocity ratio and efficiency as applied to a machine. Name the term that will not change for a machine of a given design. Derive the relationship between the three terms.

A pair of scissors is used to cut a piece of cloth by keeping it at a distance $2 \mathrm{cm}$ from its rivet and applying an effort of $10 \mathrm{kgf}$ by fingers at a distance 8 cm from the rivet. Find

(i) the mechanical advantage of scissors and

(ii) the load offered by the cloth. How does a pair of scissors act as a force multiplier or as a speed multiplier?

Draw diagrams to illustrate the positions of fulcrum, load and effort, in each of the following:
A common balance.

Draw diagrams to illustrate the positions of fulcrum, load and effort, in each of the following:
A nutcracker

Draw diagrams to illustrate the positions of fulcrum, load and effort, in each of the following:
Forceps

Write the kind of lever as an example of the human body: In raising the weight of the body on toes.