Introduction to momentum (video) | Khan Academy
Impulse is an important concept in the study of momentum. shows that an impulse is equal to a change in momentum, these two units must be equivalent, and. The problem statement, all variables and given/known data. Impulse is defined as: force x time a) Find its unit expressed in term of the base. The impulse-momentum theorem is logically equivalent to Newton's second law of motion (the force These units of impulse and momentum are equivalent.
Well, you probably have a general idea of it. If you see a big guy running really fast, they'll say, he has a lot of momentum. And if there's a big guy running really fast and a small guy running really fast, most people would say, well, the big guy has more momentum. Maybe they don't have a quantitative sense of why they're saying that, but they just feel that that must be true.Impulse - Linear Momentum, Conservation, Inelastic & Elastic Collisions, Force - Physics Problems
And if we look at the definition of momentum, it'll make sense. The definition of momentum is equal to mass times velocity. So something with, say, a medium mass and a huge velocity is going to have a big momentum.
Or something with maybe a medium mass, but-- the other way around. I forgot what I just said. So medium mass and big velocity, huge momentum, or the other way around. Huge mass, medium velocity would have maybe the same momentum, but it would still have a big momentum. Or another way of doing momentum is how little you would like to be in the way of that object as it passes by.
How unpleasant would it be to be hit by that object? That's a good way of thinking about momentum. So momentum is mass times velocity. So how does it relate to everything we've been learning so far? So we know that force is equal to mass times acceleration. Well acceleration is just change in velocity.
So we also know that force is equal to mass times change in velocity per unit of time, right? Per change in time. So force is also equal to-- well, mass times change in velocity. Mass, let's assume that mass doesn't change. So that could also be viewed as the change in mass times velocity in the unit amount of time. And this is a little tricky here, I said, you know, the mass times the change in velocity, that's the same thing as the change in the mass times the velocity, assuming the mass doesn't change.
And here we have mass times velocity, which is momentum. So force can also be viewed as change in momentum per unit of time. And I'll introduce you to another concept called impulse. And impulse kind of means that you think it means. An impulse is defined as force times time.
And I just want to introduce this to you just in case you see it on the exam or whatever, show you it's not a difficult concept. So force times change in time, or time, if you assume time starts at time 0. But force times change in time is equal to impulse.
I actually don't know-- I should look up what letters they use for impulse. But another way of viewing impulse is force times change in time. Well that's the same thing as change in momentum over change in time times change in time.
Because this is just the same thing as force. And that's just change in momentum, so that's impulse as well. And the unit of impulse is the joule. And we'll go more into the joule when we do work in all of that.
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And if this confuses you, don't worry about it too much. The main thing about momentum is that you realize it's mass times velocity. And since force is change in momentum per unit of time, if you don't have any external forces on a system or, on say, on a set of objects, their combined, or their net momentum won't change.
And that comes from Newton's Laws. The only way you can get a combined change in momentum is if you have some type of net force acting on the system. So with that in mind, let's do some momentum problems. So let's say we have a car. Say it's a car. Let me do some more interesting colors. A car with a magenta bottom. And it is, let's see, what does this problem say? So a little over a ton. And it's moving at 9 meters per second east.
So its velocity is equal to 9 meters per second east, or to the right in this example. And it strikes a stationary 2, kilogram truck. So here's my truck. Here's my truck and this is a 2, kilogram truck. And it's stationary, so the velocity is 0. And when the car hits the truck, let's just say that it somehow gets stuck in the truck and they just both keep moving together.
So they get stuck together. And if the velocity of the object is changed, then the momentum of the object is changed.
Impulse (physics) - Wikipedia
Impulse These concepts are merely an outgrowth of Newton's second law as discussed in an earlier unit. To truly understand the equation, it is important to understand its meaning in words. In words, it could be said that the force times the time equals the mass times the change in velocity.
The physics of collisions are governed by the laws of momentum; and the first law that we discuss in this unit is expressed in the above equation. The equation is known as the impulse-momentum change equation.
The law can be expressed this way: In a collision, an object experiences a force for a specific amount of time that results in a change in momentum. The result of the force acting for the given amount of time is that the object's mass either speeds up or slows down or changes direction.
What are momentum and impulse? (article) | Khan Academy
The impulse experienced by the object equals the change in momentum of the object. In a collision, objects experience an impulse; the impulse causes and is equal to the change in momentum. Consider a football halfback running down the football field and encountering a collision with a defensive back.
The collision would change the halfback's speed and thus his momentum. If the motion was represented by a ticker tape diagramit might appear as follows: At approximately the tenth dot on the diagram, the collision occurs and lasts for a certain amount of time; in terms of dots, the collision lasts for a time equivalent to approximately nine dots. In the halfback-defensive back collision, the halfback experiences a force that lasts for a certain amount of time to change his momentum.
Since the collision causes the rightward-moving halfback to slow down, the force on the halfback must have been directed leftward. If the halfback experienced a force of N for 0.
In a collision, the impulse experienced by an object is always equal to the momentum change. Depending on the physical properties of the ball and wall, the speed at which the ball rebounds from the wall upon colliding with it will vary.
The diagrams below depict the changes in velocity of the same ball.