College Physics
posted by Anonymous .
A hockey puck B rests on frictionless, level ice and is struck by a second puck A, which was originally traveling at 40.0 m/s and which is deflected 30 degrees from its original direction. Puck B acquires a velocity at a 45 degree angle to the original direction of A. The pucks have the same mass.
a) compute the speed of each puck after the collision
b) what fraction of the original kinetic energy of puck A dissipates during the collision

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a)Let final speed of A be v1, and final speed of B be v2.Using conservation of momentum, consider the horizontal:
40m = v1*cos30 + v2*cos45
and the vertical
0 = v1*sin30 + v2*sin45
In second equation, express v1 in terms of v2, then substitute into the first equation to find v2. v1 is found in similar way.
b) From a), u have the value of v1. Calculate the fraction (v1*v1)/(40*40) 
V1= 25.4
v2=14.6