Calculate the work required to be done to stop a car of $1500\ kg$ moving at a velocity of $60\ km/h$.

Given: 

A car of $1500\ kg$ is moving at a velocity of $60\ km/h$.

To do:

To calculate the work that is required to be done to stop the car.

Solution:

The mass of the car $m=1500\ kg$

Initial velocity of the car $u=60\ ms^{-1}$

Therefore, the kinetic energy of the moving car $K_1=\frac{1}{2}mu^2$

$=\frac{1}{2}\times1500\times60\times 60$

$=2700000\ Joule$

When the car stops, the velocity of the car becomes zero$( v=0)$.

Therefore, the Kinetic energy of the car at the rest position $K_2=\frac{1}{2}mv^2$

$=\frac{1}{2}\times1500\times(0)^2$

$=0$

Therefore, work done to stop the car$=$Change in energy

$=K_2-k_1$

$=0-2700000$

$=-2700000\ Joule$

Therefore, the work that is required to be done to stop the moving car is $-2700000\ Joule$. Here $-ve$ sign implies that the work should be done in the opposite direction.

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Updated on: 10-Oct-2022

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