Question

With the help of a car jack, a person lifts a $1.2$ tonne car with a force of $5000\text{N}$. Calculate the jack’s mechanical advantage. (Take $g$ = $10{\text{m s}}^{–2}$)

• A. $2.40$
• B. $1.25$
• C. $0.80$
• D. $12.50$

Answer 1

The correct option is A $2.40$

Given:

The mass of the car, $m=1.2\text{tonne}=1.2\times {10}^3\text{kg}$ $=1200\text{kg}$

Therefore, the force that the car jack has to overcome is equal to the weight of the car, i.e., the load, $L=1200\times g=1200\times 10=12,000\text{N}$

The effort applied by the person on the jack, $E=5000\text{N}$

$⟹$ Mechanical advantage of the car jack, $\text{MA}=\frac{L}{E}$
$=\frac{12,000}{5000}=2.40$

Therefore, the car jack's mechanical advantage is $2.40$.