Question

The velocity of a car increases from $54km/h$ to $72km/h$. If the mass of the car is $1500kg$, find the work done to increase the velocity.

• A. $27000J$
  
• B. $131250J$
  
• C. $0J$
  
• D. $1500J$
  

Answer 1

The correct option is B $131250J$

Initial Velocity, $u=54km/hr=15m/s$
Final velocity , $v=72km/hr=20m/s$
Mass $=1500kg$

Initial kinetic energy $\frac{1}{2}m{u}^2$

$\Rightarrow \frac{1}{2}1500\times 15\times 15=168750J$

Final kinetic energy $\frac{1}{2}m{v}^2$

$\Rightarrow \frac{1}{2}1500\times 20\times 20=300000J$

So, change in kinetic energy = work done$=300000-168750=131250J$