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OCR A Forces,Fields and Energy
Collisions and momentum
7
Physics
12th Grade
04/28/2008

Additional Physics Flashcards

 


 

Cards

Term
Define linear momentum
Definition

Momentum = mass x velocity

Units are kgms-1 or Ns

Momentum is a vector quantity, direction is very important.

Term
State the principle of conservation of momentum
Definition

If there are no external forces involved in a collision then momentum is conserved,

Total momentum before = Toal momentum after

Term
What is an elastic collision?
Definition

In an elastic collision both momentum and kinetic energy are conserved.

Momentum before = Momentum after

Ek before = Ek after

Term
What is an inelastic collision?
Definition
In a collision but kinetic energy is not conserved.
Term

What causes a change in momentum?

What is the equation for change in momentum?

Definition

A resultant force acting on an object will change its momentum.  The longer the force acts on an object, the greater the change in momentum.

Change in momentum = resultant force x time 

Term

How can force be defined in terms of momentum?

What and how is this related to Newton's 2nd law?

Definition

Resultant force = change in momentum/time taken

 

Newton's 2nd law states that the rate of change of momentum is proportional to the resultant force that produces it.

Rate of change of momentum = change in momentum / time taken = resultant force

F = Δp/t = (Δmv)/t = m(Δv/t) = ma

Term
Define Newton's 3rd law
Definition

When two bodies interact, the they exert on each other are equal and opposite.

 

It can also be written as,

Forces work in pairs.  Every action produces an equal but opposite reaction.

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