Lesson 3: Moments/ Levers/ Gears Flashcards
1
Q
What is a “moment” of a force ?
A
- A moment (of a force) is a turning effect of a force.
1
Q
What can a force/ system of forces cause an object to do?
A
- Can cause the object to rotate.
2
Q
What equation can be used to work out the size of a moment of a force?
A
Moment (Nm) = force (N) x distance (m)
3
Q
Give examples where forces cause rotation (ie. moments)
A
- wheelbarrow
- sea- saw
- opening a door
- Using a crowbar
4
Q
What distance do we use in the moments equation?
A
- The distance is the perpendicular distance from the line of action of the force to the pivot.
5
Q
If an object is balanced, what can we say about the object’s clockwise and anti- clockwise moments?
A
- If an object is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot.
6
Q
What does a lever do?
A
- A lever transmitts the rotational effect of a force.
providing input force at 1 point creates an ouput force at another point
7
Q
When using levers is the output force/ the input force greater?
A
- The output force is greater than the input force (because the point of the ouput force is CLOSER to the pivot than the point of the input force.)
- A small input force can be used to generate a large output force
8
Q
What does a simple gear system do?
A
- A simple gear system transmitts the rotational effect of forces.
9
Q
How do gears transmitt rotational effects of forces (ie. the moments?)
A
- EXAMPLE: a car engine gear connected to gear in wheel.
- Car engine gear connected to one in the wheel causing the one in the wheel the rotate.
- Gear in engine = anticlockwise direction
- Gear in wheels = clockwise direction.
- 1 gear bigger than other (turning effect of one is 2x turning effect of the other but the other rotates 2x quicker to ensure that the total work done is the same.)
