Impulsively Changing Momentum
1) A 70 kg person is traveling 30 m/s in a car. The car hits a tree but unfortunately the person was not
wearing a seat belt. The person will continue to move __________ m/s until acted on by an outside
force. This outside force will cause the person to experience an _____________ that causes their
momentum to change. The size of the _____________ equals the size of the momentum change.
a) If the steering wheel exerts the force, the person will come to a stop
in 0.05 seconds. Determine the change in momentum (impulse) for the
person when he hits the steering wheel. Fill in box (A) in chart.
b) Using the data from above, determine the force the steering wheel
exerts to stop the person. Fill in boxes (B).
c) If an air bag exerts the force, the person will come to stop in 0.25
seconds. Determine the change in momentum (impulse) for the person
when he hits the air bag. Fill in box (C).
d) Using the data above, determine the force the air bag exerts to stop
the person. Fill in boxes (D) SHOW ALL WORK IN BOXES BELOW!
Situation
Impulse
Time
Force
Person stopping on the
steering wheel.
(A)
(B)
(B)
Person stopping on the
air bag.
(C)
(D)
(D)
e) How does the person’s impulse hitting the steering wheel compare to the person’s impulse hitting the
air bag?
f) When the person hits the steering wheel, which would have a bigger force acting on the person face
or the steering wheel? Why?
f) The advantage of hitting an air bag is because the impulse is ____________ , if the time is ________
then the force is _______________.
2) A boxer gets hit in the face with by a 0.75 kg fist. The fist
was moving 15 m/s right before striking his face. The boxer’s
face will cause the fist to experience an _____________ that
causes the fist’s momentum to change. The size of the
____________ equals the size of the momentum change.
a) If the boxer is caught by surprise and doesn’t ride with the
punch (he doesn’t move his face back as he gets hit), the fist will take 0.1 seconds to stop. Determine
the change in momentum (impulse) for the fist hitting the boxer’s face. Fill in box (A) on back.
b) Using the data above, determine the force the boxer’s face will exert on the fist stopping the fist. Fill
in boxes (B).
c) If the boxer realizes he is going to get punched and rides with the punch, the fist will stop in 0.3
seconds. Determine the change in momentum (impulse) for the fist. Fill in box (C).
d) Using the above data, determine the force the boxer’s face experiences while stopping the fist while
riding with the punch. Fill in boxes (D). SHOW ALL WORK IN THE BOXES!
Situation
Impulse
Time
Force
Fist stopping without
riding with the punch
(A)
(B)
(B)
Fist stopping with
riding with the punch
(C)
(D)
(D)
e) Why will the boxer’s face experience the same force as the fist? This illustrates which law?
f) How does the impulse the fist / face experiences compare when the boxer rode with the punch versus
not riding with the punch?
g) In terms of impulse, force, and time describe the advantage of riding with
the punch?
3) Professional golfers can hit a drive over 300 yards. In order to hit a drive
that far they must change the golf ball’s momentum a lot. The golf club
imparts an ____________ on the ball that causes the ball’s momentum to
change. The size of this __________ is equal to the size of the momentum
change.
a) If an amateur golfer supplies an average force of 10000 N to a 0.046 kg golf ball for the 0.0004
seconds the club is in contact with the golf ball, determine ball’s change in momentum. (Boxes A)
b) Using the above data, determine the ball’s speed leaving the tee. (Box B)
c) The golfer takes some lessons and improves his follow through. The golfer supplies the same
average force of 10000 N to the same 0.046 kg golf ball but now the club contacts the ball for 0.0005
seconds. Determine the ball’s change in momentum (impulse) now. (Boxes C)
d) Using the data from part (c), determine the ball’s speed leaving the tee. (Box D)
e) If the golfer worked out so that now he could exert an average force of 11000 N to a 0.046 kg golf
ball for 0.0005 seconds, determine the ball’s change in momentum (impulse) now. (Box E)
f) Using the data from part (e), determine the ball’s speed leaving the tee. (Box F)
Situation
Impulse
Time
Force
Speed of ball
Weak golfer
(A)
(A)
(A)
(B)
without good
follow through
Weak golfer with
(C)
(C)
(C)
(D)
good follow
through
Strong golfer with
(E)
(E)
(E)
(F)
good follow
through
g) In terms of impulse, force, and time, describe why golfer follow through. (Boxes A-D)
h) In terms of impulse, force, and time, describe why golfers work out to get stronger. (Boxes E-F)