Forces Flashcards
The turning effect of a force is called a what?
A moment
What 2 things do moments depend on?
- The distance from the pivot to the force
- The size of the force (effort)
What do levers do to the force that you apply?
They increase the turning effect of the force that you apply.
Why is it easier to open a door when you push it further from the hinges?
Because when you push from the edge of the door, the distance between the force and the pivot is larger, so you use less effort as the moment is bigger.
How can you work out a moment?
Moment (Nm) = Applied force (N) x Perpendicular distance from pivot (m)
What are moments measured in?
Newton centimetres (Ncm) or Newton metres (Nm).
The principle of moments states that something is in equilibrium when what?
Total clockwise moment = total anti-clockwise moment
What is the spring constant?
The stiffness of a spring is called the spring constant
How can you work out the spring constant?
Force (N) = Spring constant (N/cm) x Extension (cm)
F=KxE
What is elastic behaviour?
When something returns to its original length.
What is plastic behaviour?
When something does not return to its original length so the shape is permanently changed.
Where is the elastic limit usually?
The elastic limit is often where the force and extension are no longer directly proportional.
What is the unit of mass and weight?
Mass- (kg)
Weight- (N)
What does a gram equal to a newton?
g=10N/kg
How can an object topple over if a force is applied to it?
An object will topple over if its centre of gravity is ‘outside’ the base, or edge, on which it balances. For an object to be stable it must have: a wide base. a low centre of gravity.
