P6: Forces in Action Flashcards
The Centre of Mass
The point on an object at which its mass may be thought to be concentrated.
Where is the centre of mass on a symmetrical object?
Where its axis of symmetry cross.
Test for the centre of mass of a thin sheet of material.
- Suspend the material from a stand.
- Use a ‘plumbline’ to draw a vertical line from the rod downwards.
- Repeat this process from a second point- the centre of mass will be where the two lines cross.
Oscillating Motion
Motion of any object that moves to and fro along the same line.
Simple Pendulum
A pendulum made up of a small spherical bob suspended by a string from a fixed point.
The Amplitude of an Oscillating Object:
The distance an object moves from its equilibrium position to its higher position on either side.
For a pendulum, the frequency of the oscillations is…
… the number of complete cycles of oscillation per second. (measured in Hz)
(Pendulums)
The time period (s) =
1/ Frequency of the oscillations (Hz)
Moment
The turning effect of a force.
Moments equation
Moment (nm) =
Force (n) x Perpendicular distance from the line of action of the force to the pivot (m)
When using a lever, the weight of an object is called a __, and the force a person applies is called the __.
The point around which the crowbar turns is called the __ or the __.
Load
Effort
Pivot
Fulcrum
Force Multiplier
A lever used so that a weight or force can be moved by a smaller force than it could previously.
Line of Action
The line along which a force acts.
The Principle of Moments
The sum of all the clockwise moments around a point
The sum of all the anticlockwise moments around a point
When is an object stable?
When its line of action remains within its base.
