Two friends, Al and Jo, have a combined mass of 168 kg. At an ice skating rink they stand close together on skates, at rest and facing each other, with a compressed spring between them. The spring is kept from pushing them apart because they are holding each other. When they release their arms, Al moves off in one direction at a speed of 0.90 m/sec, while Jo moves off in the opposite direction at a speed of 1.2 m/sec. Assuming that friction is negligible.

Explanation:

Let us assume that the direction in which Al is moving is in positive direction. The, according to the law of conservation of linear momentum the equation will be as follows.

           0 =

         m =

             = 96 kg

Thus, we can conclude that mass of Al's is 96 g.

the independent variable, the one that is intentionally manipulated, is whether or not the car hits the barrier.

the dependent variable, the one that you measure the response in, is the distance that the washers travel.

be subject to a force andchange its motion