Question

What is the amount of work to be done approximately on a car of mass text 1000 kg to increase its velocity from 10 km/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 1000 kg
The initial velocity of the car is 10 km/hr
On converting it into m/s,
we would get u = 2.78 m/s
Similarly, final velocity is 5.56 m/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
$\text{= 15456.8 ~J - 3864.2 ~J}$
$\text{= 11592.6 ~J}$