Question

The weight of a standard mass of 1 kg is found to be 1.7 N when it is measured using a spring balance on the moon. Next, an object of unknown mass is attached to the same spring balance, after removal of the standard mass. The new mass is found to weigh 5.1 N on the moon. What is the mass of the object?

• A. 4 kg
• B. 3 kg
• C. 2.5 kg
• D. 2 kg

Answer 1

The correct option is B 3 kg

Given:
Standard mass, $m_1=1kg$
Weight of standard mass, $W_1=1.7N$
Weight of new mass, $W_2=5.1N$

Let the new mass be $m_2$.

Weight of an object is given by:
$W=mg$
where:
$m:$ Mass of the object
$g:$ Acceleration due to gravity

Hence, ratio of weights is:
$\frac{W_1}{W_2}=\frac{m_{1}g}{m_{2}g}$
$\frac{1.7N}{5.1N}=\frac{1kg}{m_2}$
$m_2=3kg$