P3.2 Using Physics To Make Things Work Flashcards
How can you find the centre of mass of a flat object?
Weight of a string Make holes Put string in Drawn straight down Where lines cross If freely suspended an object will come to rest with it centre of mass directly below the point of suspension
What’s the centre of mass?
The centre of mass of an object is that point at which the mass of the object may be thought to be concentrated
For a symmetrical object where is the centre of mass?
Along the axis of symmetry
How do you find the time for a pendulum?
T=1/frequency
If the length of a string is doubles the frequency is _____ than half
More
What affects the time period of a pendulum?
Length of string
What’s a moment?
The turning effect of a force
How do you find the moment?
M=f x d
What is special about the distance?
It’s perpendicular from the pivot
If an object isn’t turning what can you tell?
The total clockwise moment = total anticlockwise moment
What’s total moment?
Adding the moment of all the forces on the object
What does a lever do?
Force multiplier
Load is larger than the effort
How is an object stable?
If it stays or returns equilibria when moved
How is an object supported?
Large base
Low COM
When is an object unstable?
When the line of action is outside the base,mother will be a resultant moment that causes it to topple over
Why are liquids used in hydraulics?
They are incompressible
What’s pressure and how you find it?
The force on a given area
P=f/a
Explain a hydraulic system?
Liquids are incompressible
If you push pressure is exerted in all directions
A larger area applies a larger force
A larger piston moves ____ distance?
Less
Doubling the force will move ____ the distance?
Half
What’s circular motion?
Must be pulled to the centre
Speed makes it move to the side
How are the forces imbalanced in circular motion?
Direction is changes
So velocity is
So it’s accelerating
What’s the centripetal force?
Resultant force
Force pulling it to the centre of the circle
What are the factors increase the centripetal force size?
Mass is more
Speed increases
Radius is smaller (shorter string)