7. -10 points My Notes Ask Your Teacher Two blocks are free to slide along a fri

Question

7. -10 points My Notes Ask Your Teacher Two blocks are free to slide along a frictionless wooden track ABC as shown below. The block of mass m 5.02 kg is released from A. Protruding from its front end is the north pole of a strong magnet, repelling the north pole of an identical magnet embedded in the back end of the block of mass m2 10.4 kg, initially at rest. The two blocks never touch. Calculate the maximum height to which m1 rises after the elastic collision. 5.00 m 8. Co -12 points My Notes Ask Your Teacher In an American football game, a 89.7 kg fullback running east with a speed of 4.91 m/s is tackled by a 95.8 kg opponent running north with a speed of 3.07 m/s. (a) If the collision is perfectly inelastic, calculate the speed and direction of the players just after the tackle. o (north of east) (b) Determine the mechanical energy lost as a result of the collision. Account for the missing energy

Explanation / Answer

a) for perfectly Inelastic collision,

objects move together after the collision,

APplying momentum consertion for the collision,

89.7 x 4.91i + 95.8 x 3.07j = (89.7 + 95.8)v

v = 2.37 i + 1.58j m/s

Magnitude = sqrt[2.37^2 + 1.58^2] = 2.85 m/s

Direction = tan^-1(1.58/2.37) = 33.7 deg north of east.

b) Energy lost = KEi - KEf

   = [89.7*4.91^2/2 + 95.8*3.07^2/2] - [ (89.7 + 95.8)(2.85^2)/2]

=779.34 J

Missing energy goes into Heat energy.

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