Two identical trucks have mass 5400 kg when empty, and the maximum permissible load for each is 8000 kg. The first truck, carrying 4000 kg, is at rest. The second truck plows into it at 63 km/h, and the pair moves away at 40 km/h. As an expert witness, you’re asked to determine whether the second truck was overloaded. What do you report?

1 answer

Given:
M1 = 5400 + 4000 = 9400 kg, V1 = 0.
M2 = (5400 + L) kg, V2 = 63km/h.

momentum before = momentum after.
M1*V1 + M2*V2 = M1*V + M2*V.
9400 * 0 + (5400+L)*63 = 9400*40 + (5400+L)*40,
(5400+L)*63 = 376,000 + (5400+L)*40,
(5400+L)*23 = 376,000,
5400+L = 16,348,
L = 10,948 kg = Load of truck #2.
Report: Truck #2 was overloaded.