Question

A 1800 kg car moving south at 17.5 m/s collide with a 2800 kg car moving north. The cars stick together and move as a unit after the collision at a velocity of 5.22 m/s to the north. Find the velocity of the 2800 kg car before the collision

Answer 1

v₀₂ = -2.67 m / s

Step-by-step explanation:

Let's use the conservation of the moment, for this we define a system formed by the two cars.

Consider the north direction as positive and the subscript 1 will be used for car 1 and the subscript 2 for the second car

Initial instant. Before the crash

p₀ = -m₁ v₀₁ + m₂ v₀₂

Final moment. Right after the crash

p_f = (m₁ + m₂) v

p₀ = p_f

-m₁
`v_(o1)` + m₂ v_{o2} = (m₁ + m2) v_{f}

v₀₂ =
`((m_1 +m_2) v )/(m_2)`+
`(m_1 v_(o1) )/(m_(1) )`

let's calculate

v₀₂ =
`((1800 +2800) 5.22 + 1800 (-17.5))/(2800)`

v₀₂ = -2.67 m / s

the negative sign indicates that the carriage moves in the opposite direction of the temperies