Question

What is the amount of work to be done on a car of mass 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 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.
$InitialKineticEnergy=\frac{1}{2}\times 1000\times {\left(2.78\right)}^2$
$=3864.2J$
$FinalKineticEnergy=\frac{1}{2}\times 1000\times {\left(5.56\right)}^2$
$=15456.8J$
The difference in these values would give us the amount of work done.
Work done = Change in kinetic energy
$=15456.8J-3864.2J$
$11592.6J$