Question

A cook used a ‘fire tong pair’ of length 32 cm. to lift a piece of burning coal of mass 500 g. If he applies his effort at a distance of 8 cm from the fulcrum, what is his effort? Assume friction etc. to be absent. Also, obtain values of the M.A. and the V.R. of this ‘machine’.

Answer 1

The ‘fire tong pair’ is a lever of class III in which the point of application of the effort is in between the load and the fulcrum. Hence, when friction, etc., are assumed absent, we have:

Effort × 8 cm = 0.5 kgf × 32 cm

Effort = ${\displaystyle 0.5 \text{kgf}\times \frac{32\text{cm}}{8\text{cm}}}$

= 2.0 kgf.

Thus, M.A. =${\displaystyle \frac{\text{Load}}{\text{Effort}}=\frac{0.5}{2.0}=\frac{1}{4}=0.25.}$

Also, V.R. =${\displaystyle \frac{\text{Effort arm}}{\text{Load arm}}=\frac{8\text{cm}}{32\text{cm}}=0.25.}$