Question

A vehicle spends an energy of 4000 J while moving at a constant speed of $10m{s}^{-1}$. What is the mass of the vehicle?

• A. 40 kg
• B. 60 kg
• C. 80 kg
• D. 100 kg

Answer 1

The correct option is C

80 kg

Kinetic energy $=\frac{1}{2}m{v}^2$

where, m is the mass of the body.

v is the speed of the body.

Given, K.E = 4000 J

$v=10m{s}^{-1}$

$\frac{1}{2}m{v}^2=4000$

$\frac{1}{2}\times \text{m}\times (10{)}^2=4000\text{J}$

$m=\frac{4000\times 2}{10\times 10}=80\text{kg}$