Download 02.Ch 9 notes

Ch. 9
Impulse and Momentum
Impulse (I)
force X change in time
I=FΔt
Momentum (p)
mass X change in velocity
p=mΔv
Impulse is equal to Momentum
FΔt = mΔv
or
F=mΔv/Δt
• The greater the time to stop the less the force
• The shorter the time to stop the greater the
force
• This the principle behind air bags
LT#1/LT#2
1. Momentum = ________ x _________
2. What is the momentum of an object that has a
mass of 10 kg and is moving at 10 m/s?
3. Impulse = ________ x _________
4. It takes applying 50 N of force for 3 sec to stop an
object: what impulse was applied to stop that object?
5. How much force is felt by a 10 kg object traveling
at 5 m/s, that comes to a stop in 2 sec.?
Conservation of Momentum
LT#3/LT#4
Collisions/Explosions lab
And Practice Problems
LT#5
1.
A hockey puck has a mass of 0.115 kg and is at rest. A player makes
a shot, exerting a force of 30 N for 0.16 s. With what speed does it
head toward the goal?
2. A 95 kg fullback, running at 8.2 m/s, and a 128 kg tackle collide.
Both
players end up with zero speed.
A. What was the fullback’s momentum prior to the collision?
B. What was the change in the fullback’s momentum?
C. What was the change in the tackle’s momentum?
D. How fast the tackle moving originally?
3. A 2,575 kg van collides with a 825 kg car at rest. They
move off together at 8.5 m/s. What was the original speed
of the van?