A car with a mass of 1 ton, moving in a straight line, reduced its speed from 54 km / h to 5 m / s. Find the change in momentum of the car.
m = 1 t = 1000 kg.
V0 = 54 km / h = 15 m / s.
V = 5 m / s.
The momentum of the body p is a vector physical quantity equal to the product of the body’s mass m by the speed of its movement V: p = m * V. The momentum of the body p has the same direction as the speed of movement of the body V.
p0 = m * V0.
Δp = p – p0 = m * V – m * V0 = m * (V – V0).
Δp = 1000 kg * (5 m / s – 15 m / s) = – 10000 kg * m / s.
The “-” sign indicates that the body’s impulse has decreased and the impulse change is directed in the opposite direction to the speed of movement.
Answer: the momentum of the car decreased by the value Δp = 10000 kg * m / s.
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