6.5- STABILITY Flashcards
What happens when a body in stable equilibrium is displaced then released?
returns to its equilibrium position
Why does an object in stable equilibrium return to equilibrium when it’s displaced + then released?
centre of mass of object directly below point of support when object at rest
so support force + weight directly equal + opposite to each other when object in equilibrium
but when it’s displaced, at instant of release, line of action of weight no longer passes through point of support, so weight returns to object of equilibrium
What equilibrium is a plank balanced on a drum in?
unstable equilibrium
If a plank is balanced on a drum and it is displaced slightly from equilibrium then released. what happens?
plank will role off drum
Why does the plank role off the drum when it’s slightly displaced from equilibrium then released?
centre of mass of plank directly above point of support when it’s in equilibrium
support force equal + opposite to weight
if plank displaced, centre of mass no longer above point of support
so weight acts to turn plank further from equilibrium position
Why are skittles at bowling alleys easy to knock over?
they’re tall, so centre of mass high + base narrow
What is tilting?
object at rest on surface acted on by force that raises it up on one side
When will a tilted object topple?
if it’s tilted too far
What happens to line of action of weight if an object on a flat surface tilted more + more?
line of action of weight passes closer + closer to pivot
What happens when the object is tilted too much and the line of action of its weight passes beyond the pivot?
object will topple over if allowed to
What is the position an object can be tilted to furthest without toppling?
line of action of weight passes through pivot
What can cause a tall object on a slope to topple over?
if slope too great
