Question

What is the amount of work to be done on a car of mass $\text{1000kg}$ to increase its velocity from 10km/hr to 20km/hr?

• A. 12596 J
• B. 10590 J
• C. 11592 J
• D. 13542 J

Answer 1

The correct option is C

11592 J

Mass of the car is $\text{1000kg}$.
The initial velocity of the car is $10km/hr$.
On converting it into m/s,
we would get $u=2.78m/s$.
Similarly, final velocity is $5.56m/s$.
With the mass and velocities,
we can find the initial and final kinetic energies.
$\text{Initial Kinetic Energy}=\frac{1}{2}\times 1000\times {\left(2.78\right)}^2$
$\text{= 3864.2 J}$
$\text{Final Kinetic Energy}=\frac{1}{2}\times 1000\times {\left(5.56\right)}^2$
$\text{= 15456.8 J}$
The difference in these values would give us the amount of work done.
Work done = Change in kinetic energy
$\text{= 15456.8 J - 3864.2 J}$
$\text{= 11592.6 J}$