Car and truck collision with equal mass, combined velocity 28 m/s

[graten2go]

A car heading north collides at an intersection with a truck heading east. If they lock together and travel at 28 m/s at 41° north of east just after the collision, how fast was the car initially traveling? Assume that the two vehicles have the same mass.

A) 37 m/s
B) 28 m/s
C) 74 m/s
D) 19 m/s

My friend and I are having a disagreement. I got 19 m/s and my friend got 37m/s. He is saying that the total speed would be 28m/sx2=56 m/s.

Is there any way that someone can solve the question and see what they got? Thanks.

 

[asiangrrl]

Well, it depends on which car you're talking about. I assume the car heading north.

Think about it this way. The final velocity of vector of 28 m/s has an eastward component and a northward component. Try to find just the northward component of this vector (draw it as a right triangle). I think this way you can prove your friend wrong :).