The Open Door Web Site : IB Physics : THE RELATION BETWEEN FORCE AND MOMENTUM
Explain the relationship between momentum and force. external force equals the change in momentum of a system divided by the time over which it changes. Momentum is based on an object's mass and velocity. Impulses describe force with respect to time. is the change in velocity divided by time, you can connect the two concepts with the following relationship: F • t = m • Δ v. The Relation Between Force and Momentum force = rate of change of momentum is equivalent to finding the area under the graph of force against time.
And if the velocity of the object is changed, then the momentum of the object is changed. Impulse These concepts are merely an outgrowth of Newton's second law as discussed in an earlier unit.
BBC - GCSE Bitesize: Force and momentum
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. 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. The direction of momentum depends on the direction of velocity.
The direction of force depends on acceleration. Forces can also be balanced and unbalanced.Force-Time Graph
A unbalanced force results in movement of an object. For a balanced force, the forces act in such a way that the magnitude is equal but the direction is opposite hence cancelling the net effect. For this reason an object does not move when forces are balanced and hence the velocity is zero, resulting in zero momentum. This means that forces can exist for a stationary object but the momentum is always zero for such an object.
Forces can be further classified into two types: Contact forces are those forces that are a result of actual touching between two objects, example: While, the second type of forces are those that act upon each other without any physical contact; such as gravitational force between the Earth and us. Momentum however has not been classified in such a way.
Any unbalanced force acting upon a body will result in momentum. All in all, the key thing to remember is that momentum is just a quantity that tell us about the content of motion present in a moving object, while force is a quantity that when acts upon an object changes this amount of motion.
- Force and momentum
- How is force related to momentum?
- Difference between force and momentum
Momentum is amount of motion in a moving body, whereas force is an action of push or pull. Force changes momentum of a body. Momentum and force are both vector quantities. The direction of force depends on direction of acceleration.