Alexis Lundy, Savannah Sharp, Makenna Cooper, Javier Aranguren Momentum Alexis Lundy, Savannah Sharp, Makenna Cooper, Javier Aranguren

What is Momentum? The amount of motion of a moving body, measured as a product of its mass and velocity.

State & Explain Major Concepts In chapter seven, momentum is a highlighted topic of interest. Impulse is a major player in the chapter, and is used to explain several different topics. The formula for impulse is force multiplied by the time interval. This means that the impulse equals the change in momentum of the object(s). It talks about three points in the relationship between impulse and momentum. Section one describes increasing momentum, section two is decreasing momentum over a long period of time and the third section is decreasing momentum over a short period of time. The next section talks about conservation of momentum. This section ties into Newton’s Second Law and talks about the law of conservation of momentum which states- "In the absence of an external force, the momentum of a system remains unchanged." One of the last chapters is collisions, which explains elastic collisions and inelastic collision and what these words mean. Finally, the last section is momentum vector, which says that momentum is a vector quantity because it has a size and direction which can be cancelled as well.

Historical Perspective Momentum was first introduced by Descartes before it was introduced by Newton. He came up with the formula to describe momentum; p=mv

Application of Concepts Momentum is a continuous thing that is always present in our everyday lives. Multiple examples of momentum can be seen, such as when someone kicks a soccer ball that is resting. The momentum compels the ball to move forward, while the opposite force slows your foot down after contact has been made. Another example of this in our everyday lives is if a semi-truck full of logs has to slow down before a stop light because even with a small velocity, it has a large momentum and is difficult to stop.

Think & Explain Questions (1) 1. You have greater momentum than the bicycle, if you are riding it at full speed, and it were to abruptly come to a stop, you would go flying over the handlebars, because your momentum is greater since your mass is greater. 2. When catching a fast moving baseball with your bare hand you should catch it while moving your hand back away from the ball. If you catch the ball while moving your hand towards it or in a stationary position then you would hurt your hand. 3. When an egg is thrown at a wall, it will break, but if it is thrown into a sagging sheet it does not break because the sheet has more "give" than the solid wall does. This is because an impulse is required to bring your momentum to a halt and impulse is composed of two variables- impact force and impact time. 4. Impulse is the change in momentum which is why when you fall on a floor with no give, like concrete, it hurts. When you fall on a service with some give, like wood, it hurts less. 5. No, if you throw a heavy rock while standing on a skateboard you will roll backwards, but if you simply move your hands in that same motion while standing on the skateboard you will not roll backwards.

Think & Explain Questions (2) 6. a) false b) true c) false d) false 7. This maneuver increases the impulse delivered to the shuttle because it makes the decent time to earth longer which increases the impulse because impulse is force multiplied by the time interval, by making S-curves it draws out the time which lessens the impact force. 8. The person who comes to an abrupt stop, because this means that the force was exerted at once and there wasn’t give in the floor 8. The person who bounces off the floor is in greater trouble because it takes a greater impulse to bounce than it does to fall and stop abruptly. 9. The train cars will be moving at 1.5 km/h after coupling together. 10. They observe that it is also an alpha particle because the velocity of the particle in movement was cut in half when colliding with the object at rest. This means they have the same mass.

Review Questions (1) 1. The heavy truck has a greater mass, but the rolling skateboard has greater momentum. 2. When the average force of impact on an object is extended in time the impulse increases. 3. Momentum is mass x velocity (or speed). While an impulse is the change in momentum at different instances. So if a 10,000 pound truck were to collide with a 2,000 pound car while both of them were traveling 60 km/h, the car would have less momentum. This would cause the car to stop when it collided with the truck and accelerate the opposite way, and slowly bring the truck to a stop. This is an example of momentum. An example of an impulse would be a golf club hitting a golf ball. The force that the club exerts varies from instant to instant. 4. A) it is also doubled B) Zero 5. A) four times B) four times 6. If the impulse takes longer, the force of impact will be smaller. 7. It would be four times less, then average out over time. 8. A) it will extend the impulse, and lower the impact. B) It will lower the impulse and extend the impact. 9. You would experience an impulse if you threw a ball. The ball would be at rest, and would gain momentum. The same could be said for someone catching the ball. 10. The force of impact is greater if the collision involves bouncing because the impulse that has to bring something to a stop and then back up again is greater than the impulse to just stop an object.

Review Questions (2) 11. The Pelton wheel is a better design because of the cups instead of flat paddles. The cups force the water right back out causing a greater impulse than it would with flat paddles. 12. It means that it has a direction and a size. This means that the momentum can be cancelled. 13. Newton’s Third Law proves that when firing a rifle, the force exerted on the bullet is equal to the recoil. 14. No, there is no contradiction. 15. When the momentum is considered to be conserved, it means there was no change. 16. A racket is constantly recoiling from the gases that come out of it. 17. Inelastic collision means that the object becomes distorted and generates heat. Elastic collisions mean that there are no lasting deformations and no heat that is generated. 18. Friction is an external force. it makes things that are moving slow down. 19. You would move at 2m/s. 20. Momentum is conserved when colliding objects move at an angle to each other, this is because the two momentums combine when the objects hit each other and keep going.

Background Information Momentum is the quantity of motion of a moving body, measured as a product of its mass and velocity.

Hypothesis We are investigating what happens if you drop a tennis ball on top of a basketball to the floor.

Statement of How You Will Conduct the Demonstration Hold the tennis ball directly on top of the basketball while holding both in mid-air. Then drop them simultaneously to the floor.

Materials Needed Tennis Ball Basketball

Step-By-Step Instructions 1-Hold a tennis ball on top of a basketball in the air 2-Drop them both at the same time to the floor.

Safety Precautions None

Explanation of Any Calculations Done If the tennis ball was directly in the center top of the basketball, it will shoot up into the air. The basketball will simply bounce a little, pretty much like normal.

Analysis of Results What's going on here is that when you drop the basketball and tennis ball they both have momentum (a vector) pointing down, as they fall. The basketball hits the ground an instant before the tennis ball hits the top of the basketball. So when the basketball hits the ground, the ground acts to reverse the direction of momentum of the basketball so that it's toward the tennis ball. Then when the tennis ball hits the basketball, they collide, and since momentum has to be conserved, and the mass of the basketball is much greater than the tennis ball, so the velocity of the tennis ball will have to be dramatically faster, so it shoots up into the air.

Conclusions Supported By Evidence The evidence is that the ball is going to go up in the air.

Evaluation of Hypothesis What happens is that when the basketball hits the ground, the ground reverses the direction of the basketball and hits the tennis ball colliding, and since momentum has to be conserved the tennis ball shoots up into the air.