# A2 Physics-Further Mechanics

Main subtitles are points from the specification. Notes are taken from a variety of textbooks. Note: last point has no notes as all information just tells you the equations, which are fairly self explanatory

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- Created on: 10-06-12 10:51

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Unit 4-Physics On The Move

Topic 1-Further Mechanics

Use the expression p=mv

Momentum = mass x velocity: i.e. p=mv, units kg m s¹

Momentum is a vector quantity, with both magnitude and direction.

Investigate and apply the principle of conservation of linear

momentum to problems in one dimension

Conservation of linear momentum

The linear momentum of any closed system is conserved. Linear momentum is a vector quantity

and each component is conserved independently.

When two things interact, the force exerted on one is always equal and opposite to the force

exerted on the other (Newton's third law). The interaction time is the same for both so they receive

equal and opposite impulses. This means that impulses on two colliding objects have the same

magnitude but opposite directions, meaning that the change in momentum of the two bodies is also

equal in magnitude and opposite in direction. There is no change in the total linear momentum of the

system of the two objects. This is an example of a conservation law-the two cars have interacted but

the total linear momentum is the same before and after the collision. All interactions conserve linear

momentum, and all forces arise through interactions. So the total linear momentum of the universe is

constant. For practical purposes we apply the law in a more restricted way to closed systems.

Newton's third law of motion

Forces never arise singly but always in pairs as the result of interactions

When A interacts with B the force A exerts on B is always equal to the force B exerts on A

but in the opposite direction along the same line of action

Because these pairs of forces arise from an interaction they are always of the same type:

for example, both gravitational or both electromagnetic

Action-reaction pairs always act on different bodies, never on the same body

Investigate and relate net force to rate of change in momentum in

situations where mass is constant (Newton's second law of motion)

The second law of motion

The resultant force F exerted on a body is directly proportional to the rate of change of linear

momentum p of that body

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