111 points l Previous Answers Tpier68 PO54. An 87 kg running back moving at 4.0

Question

111 points l Previous Answers Tpier68 PO54. An 87 kg running back moving at 4.0 m/s makes a perfectly My Notes O Ask Your collision? inelastic collision with a 105 kg linebacker who is initially at nest What is the speed of the players just ater their 1.81 Interactive Example O 1/2 points I Previous Answers Tplere 8 Pos5. My Notes Asa Your A 6.0 kg object with a speed of 4.0 m/s collides head-on with a 11 kg object moving toward it with a speed of 3.0 m/s. The 11 kg object stops dead after the collision (a) What is the final speed of the 6.0 kg object? X m/s 9.5 (b) Is the collision elastic? Yes No Apply conservation of linear momentum to this collision to find the post-colision speed of the objects. Decide whether the collision was elastic by examining the into and mat kinetic energies of the system.

Explanation / Answer

momentum p = mv, and
pi = pf (for an elastic collision)

mivi = mfvf
mi1vi1 + mi2vi2 = mf1vf1 + mf2vf2

The initial momentum of the system is equal to the final momentum of the system. Now, we can plug in our masses and velocities accordingly, and solve for the final speed of the 6kg object.
For the case of this example, take the 6kg object as m1 and the 11kg object as m2.

mi1vi1 + mi2vi2 = mf1vf1 + mf2vf2
(6kg)(4.0m/s) -(11kg)(3.0m/s) = (6kg)vf1 + (11kg)(0m/s)
vf1 = (57kgm/s) / 6kg

vf1 = -1.5m/s

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