Ch3 sec7 Problem Set
Impulse Momentum Theorem: 𝐹𝑡 = 𝑚Δ𝑣
Newton’s 2nd Law: FNET=ma
Δ𝑣
𝑎=
𝑡
1) A golf ball of mass .045 kg is chipped off the tee at a speed of 5 m/s. The golf
club was in contact with the ball for only 3.5 x 10 -4 s because the golfer
checked her swing.
a. Calculate the change in momentum of the golf ball.
b. Calculate the impulse applied to the golf ball.
c. Calculate the average force applied to the golf ball.
2) A golf ball of mass .045 kg is chipped off the tee at a speed of 45 m/s. The
golf club was in contact with the ball for only 3.5 x 10 -3 s because the golfer
followed through with her swing.
a. Calculate the change in momentum of the golf ball.
b. Calculate the impulse applied to the golf ball.
c. Calculate the average force applied to the golf ball.
3) In which question was the golf ball in contact with the club longer? How did
that change the impulse applied to the golf ball and the increase in
momentum of the golf ball?
4) You are the design engineer in charge of the crashworthiness of new
automobile models. Cars are tested by smashing them into fixed, massive
barriers at 14 m/s (30 mph). A new model of mass 1500 kg takes .15 s from
the time of impact until it is brought to rest.
a. Calculate the change in momentum of the car.
b. Calculate the average force exerted on the car by the barrier.
c. Calculate the average deceleration of the car.
5) A better model of a crumple zone is introduced next year and you go to test
that. This crumple zone extends impact time to .3 seconds for the same
collision as in number 4.
a. Calculate the change in momentum of the car.
b. Calculate the average force exerted on the car by the barrier.
c. Calculate the average deceleration of the car.
6) In number’s 4 and 5 explain why the car’s had the same change in
momentum but one Required more Force applied to it to bring it to a stop.
7) A football is caught by a wide receiver, which brings it to a rest. It was
thrown twice with a velocity of 20 m/s by the quarterback. The wide
receiver drops it the first pass due to the great Force it applied to his hands.
He did not give with the pass when bringing it into his hands so the contact
time between the ball and his hands was .01 seconds. On the seconds pass he
learned his lesson and allowed the ball to come to a rest over a longer period
of time, .45 seconds. For each pass calculate the
a. Change in momentum of the ball
b. Force applied to stop the ball
8) A 95 kg fullback (which is a football position) is running at 4 m/s to the east
and is stopped in .75 seconds by a head on tackler running due west.
a. Calculate the impulse exerted on the fullback and the impulse exerted
on the tackler
b. Calculate the average Force exerted on the fullback and the tackler.