force and motion Flashcards
whats the principle of momentum
momentum before = momentum after
how momentum changes
- object accelerates
- changes direction
- mass changes
what’s newtons 3rd law
when two things interact the force is equal and opposite
what happens if momentum changes quickly
force is very large
can cause injury
how crumple zones help collisions
crumple on impact
increase time to stop
decreases force
how seat belts help collisions
stretch
increase time to stop
reduces force
how air bags help collisions
increase time
reduces force
what are moments
turning effect of a force about a pivot
what’s the principle of moments
if object is balanced, total anticlockwise is equal to clockwise moment
what is the centre of gravity
the point where weight acts on an object
why centre of gravity can be off
if the object has uneven density
what happens when an object tilts
weight moves towards pivot point
why does an object fall over
if weight doesn’t act on its base
