Question

why is it difficult to stop a loaded truck then an unloaded truck​

Answer 1

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For a given speed the loaded truck has more kinetic energy than an unloaded truck. This kinetic energy must be dissipated as heat. It is undesirable to have a skid so the energy dissipation is up to the brakes.

With a loaded truck the coefficient of friction between the tyres and the road is likely to be a bit higher than with an unloaded truck. This means that the brakes can be applied somewhat harder than when unloaded so that the rate of energy dissipation can be a bit higher than when the truck is unloaded. In spite of this the increased rate of energy dissipation is insufficient to bring the truck to a halt in the same time as when the truck is unloaded.

Answer 2

Answer:

With a loaded truck the coefficient of friction between the tyres and the road is likely to be a bit higher than with an unloaded truck. This means that the brakes can be applied somewhat harder than when unloaded so that the rate of energy dissipation can be a bit higher than when the truck is unloaded.

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