4.5.4 Moments, Levers, and Gears (physics only) Flashcards
What may a force cause?
a force or a system of forces may cause an object to rotate
Moment:
- the turning effect of a force is called the moment of the force
- often use forces to cause an object to rotate
Examples of forces which cause rotation:
weight
What is the turning effect of a force called?
turning effect of a force is called the moment of the force
Formula to calculate size of the moment of a force:
How are the moments of forces affected if an object is balanced?
if an object is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot
What can be used to transmit the rotational effects of forces?
a simple lever and a simple gear system can both be used to transmit the rotational effects of forces
Pivot:
where the turning effect of the force is centred around
Why do certain objects topple?
- block on a flat surface
- the weight of the block acts directly down from the centre of mass
- tilt the block
- comes a point where the line of action of the weight lies outside of the base of the object
- now there is a resultant (unbalanced) moment acting on the block causing the block to topple
What are levers?
- levers are force multipliers
- levers transmit the turning effects of forces
What are gears?
gears transmit turning effects of a force
Where are gears found?
found in lots of different machines inc. cars, bikes, children’s toys
What are the forces 2 gears interacting with each other exert?
- Newton’s 3rd Law pairs
- exert same force on each other but have different moments
What are the moments of 2 stacked gears?
gears of same shaft which are stacked won’t have the same force but will have the same moment
What is the ratio of moments?
ratio of moments = ratio of radii = ratio of teeth
