15. Exercises

Calculate the momentum of

a) a train, of mass 120 tonnes, travelling at 40 \displaystyle \text{m}{{\text{s}}^{-1}},

b) a table tennis ball, of mass 3 grams, travelling at 4 \displaystyle \text{m}{{\text{s}}^{-1}},

c) a car, of mass 1200 kg, travelling at 36 kmph.

A ball, of mass 100 grams, is travelling horizontally at 8 \displaystyle \text{m}{{\text{s}}^{-1}} when it hits a wall and rebounds at 5 \displaystyle \text{m}{{\text{s}}^{-1}}. Assume that all the motion is perpendicular to the wall. Calculate the magnitude of the impulse on the ball.

A van, of mass of 4 tonnes, is travelling at 25 \displaystyle \text{m}{{\text{s}}^{-1}} along a straight road. As it approaches a traffic light it slows down to 8 \displaystyle \text{m}{{\text{s}}^{-1}}. Calculate the magnitude of the impulse on the van.

A ball is released from a height of 2 m and rebounds to a height of 1.4 m. Assume that no air resistance acts on the ball as it moves.

Use constant acceleration equations to find:

a) The speed of the ball when it hits the ground.

b) The rebound speed of the ball.

c) Given that the mass of the ball is 0.08 kg, calculate the magnitude of the impulse on the ball while it is in contact with the ground.

A squash ball, of mass ??? of grams, hits a wall travelling horizontally at 9 \displaystyle \text{m}{{\text{s}}^{-1}} and rebounds at 7 \displaystyle \text{m}{{\text{s}}^{-1}}. Assume that the motion is perpendicular to the wall.