Answer:
The force exerted by the brakes is 14,400,000 N
Explanation:
Initial kinetic energy of truck = 72 MJ
Work done by the breaks, W = Force exerted by the brakes × Distance, D, the truck came to stop
The distance, D, in which the truck came to a stop is given as 5 meters
Given that the initial kinetic energy, KE of the truck that was reduced by the breaks = The work done by the brakes
We have;
W = ΔKE = Change in kinetic energy
ΔKE = Initial kinetic energy - Final Kinetic Energy
Initial kinetic energy, KE = 72 MJ
Final Kinetic Energy = 0 J (Truck stopped)
ΔKE = 72 - 0 = 72 MJ
Therefore we have;
Force exerted by the breaks = W/D = 72 MJ/5 = 14.4 MN. = 14,400,000 N.
