Question

The mass of a car is $1000kg$. How much work is required to be done on it to make it move with a speed of $36km/h$?

• A. $2.5\times {10}^{4}J$
• B. $5\times {10}^{3}J$
• C. $500J$
• D. $5\times {10}^{4}J$

Answer 1

The correct option is D

$5\times {10}^{4}J$

Step 1: Given data:

The mass of a car is $\left(m\right)=1000kg$

The moving speed is$\left(v\right)=36km/h$

Step 2: Formula used:

Therefore the kinetic energy $k=\frac{1}{2}m{v}^2$ , here $m$is the mass and $v$ is the moving speed.

Step 3: Calculate the work:

The required work is equal to the kinetic energy of the car.

$$\begin{gathered} k=\frac{1}{2}\times 1000\times {\left(36\times \frac{1000}{3600}\right)}^2 \\ k=500\times {\left(10\right)}^3 \\ k=5\times {10}^{4}J \end{gathered}$$

Therefore the required work is $5\times {10}^{4}J$.

Hence, the correct option is D.