3- Making Things Work Flashcards
What can be done to increase the moment of the force?
Force must increase
The distance to the pivot must increase
What is an everyday example of moments?
It is easier to undo a wheel-nut by pushing on the end of a long spanner than a short one because the distance from the pivot is greater
What is a moment?
The turning effect of a force
What is the 1) load 2) effort?
1) the force we are trying to move
2) the force applied
Because of the lever, the effort can be much less than the load
What is the centre of mass?
Where particles mass are concentrated at a point on an object
What is object equilibrium?
An object freely suspended (balanced) - it’s centre of mass is directly below the point of suspension
The clockwise and anticlockwise moments are equal
How do you find the centre of mass of a thin irregular sheet of material (randomly cut sheet of paper)?
Suspend the sheet from a pin held in a clamp stand (make sure it’s static)
Hang a plumbline from the same pin and mark it’s position on the sheet
Hang the sheet from another point and repeat - the centre of mass is where the plumblines cross
Where is the centre of mass for a symmetrical object?
Along the axis of symmetry or where the axis of symmetry meet
What are examples of the principle of moments?
Seesaw, balance scale
Where does the line of action of the weight act?
Through it’s centre of mass
If it acts outside the base, the object will topple ((resultant moment)
What makes an object more stable?
A wider base
Lower centre of mass
(It has to tilt further before the line of action is outside the base)
About liquids in terms of pressure?
Virtually incompressible
Pressure transmitted equally in all directions
Force exerted at one point will be transmitted to other points
Makes use of hydraulic pressure systems
What is the force exerted by hydraulic pressure systems dependent on?
The force exerted on the system
The area of the cylinder at which the force acts on
The area of the cylinder that exerts the force
How can a hydraulic system be used as a force multiplier?
The use of different cross sectional areas on the effort and load sides of the hydraulic system
What is centripetal acceleration?
When an object moves in a circle (continuously changing direction/velocity) - meaning it is accelerating