# Perfect inelastic collision

1. Oct 15, 2009

### jake40208

1. The problem statement, all variables and given/known data

Two trucks with same masses are moving toward each other along a straight line with speeds of 50 mi/hr and 60 mi/hr. What is the speed of the combined trucks after completely inelastic collision?

2. Relevant equations
P$$_{}1$$+P$$_{}2$$= (2M) V$$_{}f$$

3. The attempt at a solution

Given the trucks we can assign a random mass. To make it easy Mass = 1. So 60+50= 2V$$_{}f$$ Solve it and you get 55 mi/hr. Is this correct?

Last edited: Oct 15, 2009
2. Oct 15, 2009

### zack_21

Think of the trucks as two vectors going the opposite direction. One with a magnitude of 50 mph and one with a magnitude of 60 mph. Take the sum of these two vectors.