Solve the following :

Question:

A car weighing $1400 \mathrm{~kg}$ is moving at a speed of $54 \mathrm{~km} / \mathrm{h}$ up a hill when the motor stops. If it is just able to reach the destination which is at a height of $10 \mathrm{~m}$ above the point, calculate the work done against friction (negative of the work done by the friction).

Solution:

Work done,

$\mathrm{W}=\left(0+\frac{1}{2} \mathrm{mv}^{2}\right)-\mathrm{mgh}$

$W=\left[^{\frac{1}{2}} \times 1400 \times 15^{2}\right]-[1400 \times 9.8 \times 10]$

$W=20300 \mathrm{~J}$

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