Speed after collision of a truck

[KatieLynn]

Homework Statement

A 7500kg truck traveling at 5 m/s east collides with a 1500kg car moving at 20 m/s direction south of west. After the collision, the two vehicles remain tangled together. A) With what speed and direction does the entangled wreckage move immediately after the collision? B) If the coefficient of friction between the sliding wreckage and the road is .85, how far will the wreckage go before it slides to a stop?

Homework Equations

The Attempt at a Solution

A) (7500kg)*(5m/s) + (1500kg)*(20m/s) = )7500kg+1500kg)V
V= 7.5 m/s
is that right?

 

[dynamicsolo]

A 7500kg truck traveling at 5 m/s east collides with a 1500kg car moving at 20 m/s direction south of west. After the collision, the two vehicles remain tangled together.

You can't just add the momenta of the vehicles because they did not meet along the same line. I'm afraid you're forced to use vectors for this problem.

 

[ogb p]

B) To find the distance traveled before stopping, we can use the equation d = (v^2)/(2μg), where d is the distance, v is the initial velocity, μ is the coefficient of friction, and g is the acceleration due to gravity (9.8 m/s^2). Plugging in the given values, we get:
d = (7.5 m/s)^2 / (2*0.85*9.8 m/s^2) = 0.97 meters
Therefore, the wreckage will slide for approximately 0.97 meters before coming to a stop.