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ssm As an aid in working this problem, consult Concept Simulation 7.1 . Two frie

ID: 1674116 • Letter: S

Question

ssm As an aid in working this problem, consult Concept Simulation 7.1.

Two friends, Al and Jo, have a combined mass of 168 kg. At an iceskating rink they stand close together on skates, at rest andfacing each other, with a compressed spring between them. Thespring is kept from pushing them apart because they are holdingeach other. When they release their arms, Al moves off in onedirection at a speed of 0.80 m/s, while Jomoves off in the opposite direction at a speed of 1.5 m/s. Assuming that friction is negligible, findAl's mass.
1 kg

Explanation / Answer

Call the masses M and   m . we know, from cons ofmomentum       0.80 M = 1.5m           and     M + m = 168 .      where M is Al's massand   m is Jo's mass . So...       0.80 M = 1.5 (168 - M)   .        0.80 M + 1.5M =   1.5 * 168 .         2.3 M =    252 . M =   109.6 kg