Physics of Collision . Elastic and Inelastic Collision.

Physics of Collision . Elastic and Inelastic Collision.

1a) In hockey, bumps and checks are useful to throw an opponent off. Even small, unexpected
changes in his velocity can disrupt an opponent’s timing. In a game, an 80-kg player skating at
10 m/s overtakes and bumps from behind a 100-kg player moving in the same direction at 8 m/s.
As a result, the 100-kg player’s speed increases to 9.42 m/s.
1)How fast is the 80-kg player moving after the bump? Round the final answer to three decimal
places.

2)Calculate the coefficient of restitution associated with the collision. Round the final answer to
four decimal places.
1b)
A 0.35-kg tennis racquet moving to the right at 26 m/s hits a 0.06-kg tennis ball that is moving to
the left at 36 m/s. After the collision, the racquet continues to the right, but at the reduced speed
of 16 m/s.
1)What is the total momentum of the ball–racquet system before the collision? Round the final
answer to three decimal places.
kg m/s

2)Calculate the ball’s speed after the collision. Round the final answer to two decimal places.
m/s
3)What is the coefficient of restitution? Round the final answer to two decimal places.
4)Using a contact time of 6 ms, determine the peak force on the ball in the collision. Round the
final answer to three decimal places.
lb
1c) A punter in a game of football launches the ball at 52.1 mph at an angle of 75.9° with respect
to the horizontal. Ignore the effects of air and treat the punt using free-fall kinematic equations.

The mass of the football is 0.42 kg.
1)Calculate the ball’s kinetic energy just as it leaves the punter’s foot. Round the final answer to
two decimal places.
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2) What is the ball’s speed at the highest point in its flight? Round the final answer to two decimal
places.
m/s
3) Calculate the ball’s kinetic energy at the highest point in its flight. Round the final answer to
three decimal places.
J
4) Determine the gravitational energy of the ball at its highest point. Round the final answer to
one decimal place.
J
5) Determine the gravitational and kinetic energy of the ball halfway up to its highest point.
Round the final answers to two decimal places.
Gravitational energy =
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Kinetic energy =
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6) The bullet from a typical 0.357 Magnum pistol is 8 g and listed muzzle velocities are typically
about 1400 ft/s. Compare the kinetic energy of a just-punted football to such a bullet. Calculate
the percentage of increase in the kinetic energy of the ball when compared to that of the bullet.
Round the final answer to the nearest whole number.
%
7) Due to air drag, the ball was measured to hit the ground at 38 mph. Calculate the thermal
energy that was generated by the ball’s passage through the air. Round the final answer to one
decimal place.
J