How much work must be done to stop an 1 800kg vehicle travelling at 30 m/s?

810 kJ

Explanation:

Work done is equal to change in kinetic energy

W=∆KE

Change in kinetic energy is given by

∆KE=½m (v²-u²)

Where ∆KE is the change in kinetic energy, m is mass of the vehicle, v is final velocity while u is initial velocity.

Since the vehicle must come to rest, the final velocity is zero.

Substituting 1800 kg for m, 0 m/s for v and 30 m/s for u then

∆KE=½*1800 (0²-30²) = -810, 000J

Converted into kJ

∆KE=-810 kJ

Therefore, work done is 810 kJ