Question

A 2000 kg minivan runs into a 800 kg car that was at rest at a stop sign and they stick together. If the compact car does not stick to the van but, instead, causes the minivan to come to a complete stop. How fast will the car be going after the collision?

Answer 1

v₂ = 2.5 v₁

car leaves at 2.5 times the speed of the minivan

Step-by-step explanation:

This is an exercise of conservation of the momentum, to solve it we create a system formed by the minivan and the car, therefore during the crash the forces are internal and the momentum is conserved.

Initial instant. Before the crash

p₀ = M v₁+ 0

Final moment. After the crash

`p_(f)` = M 0 + m v₂

how momentum is conserved

p₀ = p_{f}

M v₁ = m v₂

v₂ =
`(M)/(m)` v₁

let's calculate

v₂ = 2000/800 v₁

v₂ = 2.5 v₁

therefore the car leaves at 2.5 times the speed of the minivan