# Linear momentum force relationship between length

### What are momentum and impulse? (article) | Khan Academy

The useful thing about momentum is its relationship to force. and internal to a system is also fundamental to understanding conservation of momentum. However, it turns out that conservation of momentum can be deduced from Newton's Defining work as force x distance, as usual we will measure distance in. Distance, Velocity, Momentum, Force, Pressure, Work and Energy angular momentum: L = pr, where p is the linear momentum and r is the radius of the circle.

Real-World Applications As mentioned in the previous part of this lessonmomentum is a commonly used term in sports.

## Momentum, Work and Energy

When a sports announcer says that a team has the momentum they mean that the team is really on the move and is going to be hard to stop. The term momentum is a physics concept. Any object with momentum is going to be hard to stop. To stop such an object, it is necessary to apply a force against its motion for a given period of time.

**Momentum (2 of 9) Momentum and Force**

The more momentum that an object has, the harder that it is to stop. Thus, it would require a greater amount of force or a longer amount of time or both to bring such an object to a halt. As the force acts upon the object for a given amount of time, the object's velocity is changed; and hence, the object's momentum is changed.

The concepts in the above paragraph should not seem like abstract information to you. You have observed this a number of times if you have watched the sport of football.

In football, the defensive players apply a force for a given amount of time to stop the momentum of the offensive player who has the ball. You have also experienced this a multitude of times while driving.

As you bring your car to a halt when approaching a stop sign or stoplight, the brakes serve to apply a force to the car for a given amount of time to change the car's momentum. An object with momentum can be stopped if a force is applied against it for a given amount of time. A force acting for a given amount of time will change an object's momentum. Put another way, an unbalanced force always accelerates an object - either speeding it up or slowing it down.

If the force acts opposite the object's motion, it slows the object down. If a force acts in the same direction as the object's motion, then the force speeds the object up.

Either way, a force will change the velocity of an object. And if the velocity of the object is changed, then the momentum of the object is changed.

### Impulse & Momentum - Summary – The Physics Hypertextbook

Impulse These concepts are merely an outgrowth of Newton's second law as discussed in an earlier unit. Because of the impulse-momentum theorem, we can make a direct connection between how a force acts on an object over time and the motion of the object.

One of the reasons why impulse is important and useful is that in the real world, forces are often not constant.

Forces due to things like people and engines tend to build up from zero over time and may vary depending on many factors. Working out the overall effect of all these forces directly would be quite difficult.

When we calculate impulse, we are multiplying force by time.

- Momentum Conservation and Newton’s Laws
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This is equivalent to finding the area under a force-time curve. This is useful because the area can just as easily be found for a complicated shape—variable force—as for a simple rectangle—constant force.

### How is force related to momentum?

It is only the overall net impulse that matters for understanding the motion of an object following an impulse. Watch this video on area under rate function to learn more about how to use the area under a curve to evaluate the product of the quantities on the axes. The concept of impulse that is both external and internal to a system is also fundamental to understanding conservation of momentum.