Impulse
Define Impulse
The force exert on/by an object times the time this force is applied.
Define Change in Momentum
The change in an object's velocity times its mass
Define an Elastic Collision
This is a collision in which two or more objects bounce off of each other
Define an inelastic collision
A collision in which two or more objects collide, stick and travel together.
What sports highlight momentum? Must be able to list 3 of the sports
Football, golf, baseball, tennis, hockey, lacrosse, soccer, rugby, bowling
Equation for impulse
J= F X t
Equation for change in momentum
Delta P= M x Delta V
What is the general equation for this type of collision?
m1v1 + m2v2 = m1v1' +m2v2'
General equation for Inelastic collisions
m1v1 + m2v2 = (m1+ m2) V
How do car crashes involve impulse=change in momentum?
The car changes its momentum and delivers an impulse to the rider/driver
Units of Impulse
Ns
The Units of Change in Momentum
Kg m/s
What is conserved in an elastic collision?
Momentum and Kinetic Energy
Why is energy not conserved in an inelastic collision
Energy is lost in the deformation of the objects, the sound of crumpling materials and the heat created.
How can a car lessen the impulse delivered to the driver/passenger of a car?
Seat belts and/or air bags lessen the impulse force delivered
Impulse on a 200g cart that is pushed by a 120 N for 5 ms.
0.6 Ns
What is the change in momentum of a 400 g cart that is traveling 5 m/s and stops in 20 s?
-2 kg m/s
A 400 g cart is traveling to the right at 4 m/s and strikes a 200 g cart traveling to the left at 3 m/s. The 400 g cart travels to the right after this collision at 0.05m/s what is cart 2's final speed?
4.9 m/s to the right.
A 2 g bullet strikes a 4 kg stationary block and sticks inside the block. The block and bullet travel together at 1.3 m/s after this collision. How fast was the bullet traveling before it struck the block?
2601 m/s
How do seat belts and air bags lessen the force of impact in a car crash?
Seat belts and air bags lessen the blow or impact force by lengthening the time over which the momentum is changed.
What type of graph will give the impulse on an object and how is the graph used?
A Force vs. time graph. The area below the curve
How can an object change its momentum without changing its speed (two answers are required)?
Change its direction and/or change its mass
When a ball bounces off of the ground, why does the ball never reach the same height it was dropped from? Must use momentum to partially explain your answer.
Energy is lost in the collision with the ground so this is not a completely elastic collision or some momentum is lost to the ground. Heat, sound and chemical energy are lost.
How could the graph of an inelastic collision be used to demonstrate the conservation of momentum? What would be on the Y, X axis and how would the line of the graph be used?
Y- Pf, X- Pi and the slope would be used to see if momentum was conserved. If so the slope would be 1.
Describe in detail how a rocket demonstrates the law of conservation of momentum
The rocket starts with zero momentum. This means after the rocket's engines are fired the momentum of the system remains zero. This is accomplished by the momentum of the rocket in the forward direction being cancelled by the hot exhaust being ejected out the back of the rocket. Mv = mV
(large mass)(small velocity)= (small mass)(Large velocity)