Chapter 6 Flashcards
If an object is stationary, what is the value of the resultant force?
0
What 5 factors will any measurement have?
- Quantity
- Magnitude
- Unit
- Error
- Scalar or vector
When can a measurement be a scalar?
When it just has a magnitude/amount
When can a measurement be a vector?
When it has a magnitude and a direction
How do you model a vector?
Using straight arrows with a direction
When modelling a vector, why is the size and length of the arrow important
Because it indicates the magnitude as you must declare a scale
How do you get a resultant force from parallel vectors?
Add them numerically
How do you get a resultant force from anti-parallel vectors
Add them numerically
How do you get a resultant force from perpendicular vectors?
Pythag or trig
Define the principle of moments
The moment of a force about any point is defined as the force X the perpendicular distance from the line of action of the force to the point
Define the principle of moments
For a system in equilibrium, the sum of clockwise moments = the sum of anti clockwise moments about any given point
Define centre of mass
The centre of mass on a body is the point at which a single force on the body has no turning effect
What must be satisfied in order to have a couple?
Must have 2 forces equal in size and in opposite direction
A body is at rest and a force is used to disturb the body. What happens if the body returns to its original position?
It is stable
A body is at rest and a force is used to disturb the body. What happens if the body doesn’t return to its original position?
It isn’t stable
What must be true about the weight and the pivot if the system is to be in equilibrium
The weight is in line vertically with the pivot point
What happens if the COM is above the pivot point in relation to stability?
The object is unstable
What happens if the COM is below the pivot point in relation to stability?
The object is stable
Define toppling
The system is tilted up to a balance point, then pushed a bit further and topples over
What can you say if a system is in equilibrium?
The resultant force is 0, and the principle of moments applies (clock and anti clock are equal)
What does a free body force diagram show?
Shows all the forces acting on a body
When do you use a triangle of forces diagram?
When funding the value of the forces or the resultant force
