Car A, of mass 9300 kg travels at 25 m/s in the +x direction and collides with C
ID: 1696566 • Letter: C
Question
Car A, of mass 9300 kg travels at 25 m/s in the +x direction and collides with Car B, moving towards Car A at -15 m/s (in the -x direction). The two cars stick together and move off with speed 6.0 m/s in the +x direction the collision is inelastic.
a) use the conservation of momentum to determine the mass of Car B.
b) after sticking together the cars slide some distance before coming to rest. Assuming that friction between the wheels and the road is the only force acting determine the work done by the frictional force.
c)The distance traveled by the cars after the collision was measured to be 12 m. Use the work-energy princciple to determine the magnitude and direction of the frictional force acting
d) calculate the coefficient of friction of the surface
Explanation / Answer
mA = 9300 kg, vA = 25 m/s, vB = -15 m/s, u = 6.0 m/s, d = 12 m
a) use the conservation of momentum to determine the mass of Car B.
mAvA + mBvB = (mA + mB)u
mB = mA(vA - u)/(u - vB) = 8414 kg
b) the work done by the frictional force
W = (mA + mB)u2/2 - (mAvA2/2 + mBvB2/2) = -3.53*106 J
c) the magnitude frictional force = F
W = F*d
F = -2.95*105 N
-x direction
d) the coefficient of friction of the surface =
|F| = (mA + mB)g
= 1.70