Using Physics To Make Things Work Flashcards
How do you increase the moment
Either the force must increase
Or the distance to the pivot must increase
Why is it easier to undo a wheel nut with a long spanner than a short one
The longer spanner increases the distance between the line of action of the force and the pivot
What is used to make a Job easier
A lever
What is the load
The weight of an object raised by a device used to lift the object or the force applied by a device when it is used to to shift an object
What is the effort
The force applied to a device used to raise a weight or shift an object
What does a lever act as
A force multiplier, so the effort we apply can be much less than the load
What’s a moment
The turning effect of a force
What are moments measured in
Newton metres
What is the line of action p
The line along which a force acts
What is a pivot
The point about which an object turns when acted on by a force that makes it turn
What is the centre of mass
The point where an objects mass may be thought to be concentrated
What is equilibrium
The state at which an object is as rest
How can you find the centre of mass of a thin irregular sheet of a material
Suspend the thin sheet from a pin held in a clamp stand. Because it is freely suspended, it is able to turn
When it comes to rest, hang a plumbline from the same pin
Mark the position of the plumbline against the sheet
Hang the sheet with the pin at another point and repeat the procedure
The centre of mass is where the lines that marked the position of the plumbline cross
What does the position of the centre of mass depend on
The shape of the object and it sometimes lies on the outside of the object
Where is the centre of mass for a symmetrical object
Along the axis of symmetry, if the object has many symmetry lines the centre of mass is where the lines of symmetry meet
If an object is in equilibrium it is …..
Balanced
If you take the moments at any point what will you find
The total clockwise moment and the total anti-clockwise moments are equal
What is the principle of moment
For an object in equilibrium, the sum of all the clockwise moments about any point = the sum of all the anti-clockwise moments about that point
What does the line of action of the weight of an object act through
The centre of mass
What is a resultant moment
The difference between the sum of the clockwise moments and the anti-clockwise moments about the same point if they are not equal
If the line of action of the weight lies outside the base of an object what happens
There will be a resultant moment and the object will topple over
The wider the base of an object and the lower its centre of mass……..
Further it has to tilt before the line of action of the weight moves outside the base
How is the stability of an object increased
Making its base widget and its centre of mass lower
What is pressure measured in
Pascals, Pa or N/m2
