Question

calculate the work done by the breaks of a car of mass 1000kg when it's speed reduced from 20m/s to 10m/s​

Answer 1

Answer:

150 kj

Explanation:

1000x300/2 = 150 kj

Answer 2

Answer:

Work done will be equal to change in kinetic energy of car

$since \: kinetic \: energy = \frac{1}{2} m {v}^{2} \\ \\ w = \frac{1}{2} m \times {10}^{2} - \frac{1}{2} m \times {20}^{2} \\ \\ w = \frac{1}{2} \times 1000(100 - 400) \\ \\ w = - 150000 \: j = 150 \: kj$