8.27 wo cars collide at an intersection. Car A , with a mass of 1900 kg , is goi

Question

8.27

wo cars collide at an intersection. Car A, with a mass of 1900 kg , is going from west to east, while car B , of mass 1500 kg , is going from north to south at 12.0 m/s . As a result of this collision, the two cars become enmeshed and move as one afterward. In your role as an expert witness, you inspect the scene and determine that, after the collision, the enmeshed cars moved at an angle of 60.0 south of east from the point of impact.

A. How fast were the enmeshed cars moving just after the collision?

ANSWER: ___________ m/s

B. How fast was car A going just before the collision?

ANSWER:___________ m/s

Explanation / Answer

For Car A:
p=mv
p=1900*u Ns (use u as velocity so there is no confusion later on)
For Car B:
p=mv
p=1500*12
p=18000 Ns
For Enmeshed Cars:
m=1900+1500
m=3400kg
p=mv
p=3400*v Ns
Resolve Vectors:
theta=60 degrees
Adjacent=1900*u
Opposite=18000
Hypotenuse=3400*v

A)
sin(theta)=O/H
sin(60)=18000/(3400*v)
v=18000/(3400*sin(60))
v=6.1m/s
The enmeshed cars are moving at 6.1m/s.

B)
tan(theta)=O/A
tan(60)=18000/(1900*u)
u=18000/(1900*tan(60))
u=5.46m/s
Car A is moving at 5.46m/s, just before the collision.

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