Download AP Impuworksheet

AP Physics Supplemental Problems:
Impulse & Momentum
Name _________________________
Date _______________ Per _____
The equation I  Ft  p is just another form of Newton's 2nd law F  ma , and for many
purposes it is a more useful form. The following problems are to give you a simple
introduction to the use of this impulse-momentum equation. When working the following
problems, remember that both impulse and momentum are vector quantities and must be
added and subtracted according to vector rules. Since the following problems are onedimensional, "+" and "_" can be used for the directions of the vector quantities. In each
problem below, let the direction the ball is traveling after it is kicked be the "+" direction.
1. As a soccer ball rolls along the ground, a student kicks it in the direction it is rolling,
applying an average force of 200 N to the ball. If the ball's mass is 0.5 kg and the kick
lasts about 1/50 second, what is the resulting change in velocity of the soccer ball?
Solution: An average force of _______ N was applied to the ball for _______ s.
The impulse applied to the soccer ball by F ave in time t is given by
I  Fave t  (__________)(__________) = __________.
Since I  p , the resulting change in momentum of the ball is __________.
Recalling that p  mv f mvi  m( v ) , the resulting change in velocity of the ball, v ,
is
given by
v  p / m  (__________)/(__________) = __________.
2. Another student kicks a soccer ball that is initially at rest. After the kick the speed of the
ball is 14 m/s. If this kick also lasts for about 1/50 second, estimate the average force
applied to the ball by the student's foot.
Solution: The change in momentum, p , as a result of the kick = __________
The impulse, I , applied to the ball during the kick = __________
Since the kick lasted _______ second, and I  Fave t  p , then F ave  __________.
3. At another time the student kicks a soccer ball rolling toward her with a speed of 10
m/s. After the kick the ball moves in the opposite direction with a speed of 14 m/s. If
the kick again lasts about 1/50 second, estimate the average force applied to the ball by
the student's foot.
Solution: p i  of the ball = __________
pf of the ball = __________
p of the ball = __________ and thus, the I applied to the ball = __________.
Since the kick lasted _______ seconds, then F ave  __________.