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A Change in Momentum Takes Force and Time… The More Time, the Bigger Change:
∆
p = mv
f
 mv
i
=
Σ
F
∆
t
1.
A 50kg carton that slides across an icy surface with a velocity of 4 m/s.
a.
What is its momentum?
b.
The sliding carton skids onto a rough surface and stops in 3 seconds.
What is the frictional force
it encounters?
2.
An average force of 45N is exerted on a cart of 2.5 seconds, as shown:
a.
What is the impulse that occurs?
b.
What is the change in momentum of the cart?
c.
If the mass of the cart is 15 kg, and the cart was initially at rest, what is
the velocity of the cart after 2.5 seconds?
3.
A 0.4 kg soccer ball approaches a player horizontally with a velocity of 18 m/s to the north.
The
player strikes the ball and causes it to move in the opposite direction with a velocity of 22 m/s.
a.
What is the change in momentum (
∆
p) for the ball?
Hint:
Sketch the momentum vectors,
remembering that when you subtract one vector from another, you are adding a negative vector.
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 Spring '11
 Matthews
 Biology, Kinetic Energy, Mass, Momentum, Collision, m/s

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