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Worksheet: Conservation of Linear Momentum


A paving truck with a mass of kg drives in a straight line at 2.5 m/s and dumps kg of gravel on the road, taking negligible time. What is the speed of the truck after dumping the gravel?


A figure skater whose mass is 75 kg moves at 6.2 m/s towards his 50-kg-mass partner. The skater’s partner is moving at 5.5 m/s, in the same direction as the skater. When the skater catches up with his partner, he picks her up, without exerting any horizontal forces on his skates. What speed does the skater move at while he is lifting his partner?


A cyclist of mass 60.0 kg sits on a bicycle of mass 10.0 kg, moving at 15 m/s in the positive -direction. A bug of mass 5.0 g splatters on her cycle helmet. The bug was initially moving at 2.0 m/s in the same direction as the cyclist.

What is the combined momentum of cycle and cyclist before colliding with the bug?

  • A kg.m/s
  • B kg.m/s
  • C kg.m/s
  • D kg.m/s
  • E kg.m/s

What is the initial momentum of the bug?

What is the change in the cyclist’s velocity due to colliding with the bug?

If the bug had been moving in the opposite direction to the cyclist, how much of a velocity change would have resulted from the collision?


Train cars are coupled together by being bumped into one another. Suppose two loaded train cars are moving toward one another, the first having a mass of kg and a velocity of , and the second having a mass of kg and a velocity of . What is their final velocity?


A 5.00-kg squid that is initially at rest ejects 0.250 kg of fluid with a velocity of 10.0 m/s. The squid moves in the direction opposite to the direction of the ejected fluid. A 5.00-N frictional force opposes the squid’s movement.

What is the recoil velocity of the squid if the ejection is done in 0.100 s?

How much energy is lost to work done against friction?


A 35 kg child sleds down a hill and then coasts along the flat section at the bottom, where a second 35 kg child jumps on the sled as it passes by her. If the speed of the sled is 3.5 m/s before the second child jumps on, what is its speed after she jumps on?


An initially stationary football player of mass 90 kg catches a football of mass 0.50 kg that is thrown to him with a horizontal speed of 17 m/s and negligible vertical speed. What is the horizontal speed of the football player after catching the ball?

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