Question

Calculate the work required to stop the car of 1500 kg moving with a velocity of 72 km/h by applying brakes

Answer 1

$\boxed{\red{Work\:done=Change\:in \:kinetic\:energy}}$

$u(initial \: velocity) = 72km {hr}^{ - } = 20m {sec}^{ - } \\ \\ kinetic \: energy = \frac{1}{2} m {v}^{2} \\ \frac{1}{2} \times 1500 \times 20 \times 20 \\ 3 \times {10}^{5} joules$
work to be done to stop a car is $\boxed{\blue{300000\:joules}}$