Answer
See the detailed answer below.
Work Step by Step
The given formula appears as a conservation of the momentum of two vehicles that are stuck together after they hit each other.
a) A truck, of mass 2000 kg is moving to the right at a speed of 5 m/s, collides with a car, of mass 1000 kg that is moving to the left at a speed of 4 m/s. it is a head-to-head collision. If the two vehicles become entangled and slide as one body, what is their final speed?
________________________________________________
b) See the pictorial representation below.
$$v_{fx}=\dfrac{(2000\times 5)+(1000\times -4)}{3000}=\color{red}{\bf 2}\;\rm m/s$$
