Answer:
An average lorry at 60kmph
Explanation:
According to the work-energy theorem, the work done by the brakes (W) is equal to the change in kinetic energy (ΔKE). Work is equal to force (F) times distance (d), and kinetic energy is half the mass (m) times the square of the speed (v).
W = ΔKE
Fd = ½ mv²
For the same distance, an object with more mass or more speed will require a greater braking force.
The lorry has a very large mass, and a high speed.
The cat has a very small mass, and a high speed.
The moped has a small mass and a very high speed.
The bicycle has a small mass and a low speed.
Of the four, the lorry has the greatest combination of mass and speed. Therefore, it will require the greatest braking force.
