VISUAL PHYSICS ONLINE

2 DYNAMICS

P20 014

Trolley A has a mass of 2.00 kg and trolley B has a mass of 4.00 kg. They are held against a compressed spring which is not attached to either trolley. The trolleys are released and move away from each other along a straight line as the compressed spring pushes them apart. After the initial acceleration, trolley A moves at a constant speed of 0.400 m.s^-1.

Draw a displacement / time graph showing the motion of both trolleys when they are moving with constant velocities for the time interval of 5.00 s .

View solution below only after you have completed the answering the question.

Solution

Event #1 both trolleys at rest

Initial momentum of System of both trolleys

Event #2 both trolleys are moving with constant velocities

Final momentum of System of both trolleys

since momentum must be conserved as the spring pushes the trolleys apart.

The two trolleys move in opposite directions along a straight line.

The slope of the displacement / time graph is equal to the velocity and since the velocity is constant, the displacement / time graph will be a straight line through the Origin. After 5.00 s, the displacements of trolley A and B are