Download Momentum Notes

Physics Momentum Notes I
Name______________________________ Period ______
Resource:
http://www.physicsclassroom.com/Class/momentum/momtoc.html
Inertia:
Why is a bullet that is thrown not as dangerous as a bullet that is
fired from a rifle?
_________________________________________________
Momentum is ________________ in motion.
_________________________ is the product of the mass of a
moving body and its velocity.
momentum () = m  Δv
SI Unit for momentum: ______________
Example 1:
An ostrich with a mass of 146kg is running to the right with a velocity of 17m/s. Find the
momentum of the ostrich.
Example 2:
What velocity would a 5.5g bullet have, if its momentum was the same as the ostrich in the
previous problem?
Example 3:
A car possesses 20 000 units of momentum. What would be the car's new momentum if:
A. its velocity were doubled
B. its velocity were tripled
C. its mass were doubled (by adding more passengers and a greater load)
D. both its velocity were doubled and its mass were doubled.
Physics Momentum Notes I
Name______________________________ Period ______
How can you change momentum of an object?
What term describes a change in velocity?
How do you change the velocity, ie cause acceleration?
As force increases, what happens to momentum?
Will the change be instantaneous?
Impulse:
Impulse = (Ft)
SI Unit for impulse: ______________
As impulse increases what do you think happens to momentum?
What happens to momentum if the impulse decreases?
(Ft) = m  v = m(vf-vi) = p
SI Unit for momentum: ______________
SI Unit for impulse: ______________
How can these be equal?
In simple terms, a ___________ force acting for a long time can produce the same change in momentum as a
large force acting for a ________ time
Physics Momentum Notes I
Name______________________________ Period ______
Increasing Momentum
Why would you want to increase momentum?
Example 4:
A hockey puck has a mass of 0.12 kg and is at rest. A hockey player makes a shot, exerting a
constant force of 30.0 N on the puck for 0.1 s. With what speed does it head toward the
goal?
Example 5:
A hockey puck has a mass of 0.12 kg and is at rest. A hockey player makes a shot, exerting a
constant force of 30.0 N on the puck for 0.16 s. With what speed does it head toward the
goal? How did following through affect the velocity of the puck compared to example 4?
Example 6:
A hockey puck has a mass of 0.12 kg and is at rest. A hockey player makes a shot, exerting a
constant force of 36.0 N on the puck for 0.1 s. With what speed does it head toward the
goal? How did following through affect the velocity of the puck compared to example 4?
Example 7:
A hockey puck has a mass of 0.12 kg and is at rest. A hockey player makes a shot, exerting a
constant force of 36.0 N on the puck for 0.16 s. With what speed does it head toward the
goal? How did following through affect the velocity of the puck compared to example 4?
Conclusion for the Hockey Player:
Physics Momentum Notes I
Name______________________________ Period ______
Decreasing “Momentum”
You are driving at 50 mph and lose control of your car. You can hit a wall or a haystack. Which do
you choose? Why?
How is the momentum different?
What is different?
Example 8:
A 1400kg car is travelling westward at a velocity of 15m/s, when it veers off the road and
collides with a pole and is brought to rest in 0.30s. How much force is exerted on the car
during the collision?
Example 9:
A 1400kg car is travelling westward at a velocity of 15m/s, when it veers off the road and
instead of colliding with a pole it collides with a barrier of sand and is brought to rest in
0.70s. How much force is exerted on the car during the collision? How does this force
compare to previous example?
Physics Momentum Notes I
Name______________________________ Period ______
Law of Conservation of Momentum
m1v1  m2v2  m1v1'  m2v2'
Inelastic Collisions (Join)
Objects with a the same velocity after the event
Two
Ex A: A grandma is roller skating at 6 m/s and collides with a little boy who is stationary. If grandma has a mass
of 80 kg and the boy has a mass of 40 kg, what is their velocity after impact?
Elastic Collisions (Bounce)
Two Objects with two individual velocities after the event
Ex B: Two people are practicing curling. The red stone is sliding on the ice towards the west at 5.0 m/s and has a
mass of 17.0 kg. The blue stone has a mass of 20.0 kg and is stationary. After the collision, the red stone moves
east at 1.25 m/s. Calculate the velocity of the blue stone after the collision.
Explosions (Separate)
Object to start. Splits into two individual velocities in opposite directions after the event
One
Ex C: A 63.0kg astronaut is on a spacewalk when his tether to the shuttle breaks. He is able to throw a 10.0kg
oxygen tank away from the shuttle with a velocity of 12.0m/s. Assuming he started from rest, what is his velocity?