Mechanics Flashcards
What is a scalar?
A quantity which has only magnitude, not direction.
What is a vector quanitity?
A quantity with both magnitude and direction.
How to find if a quantity is vector or scalar?
1) Convert to base units
2) If there is a vector ^ 2 ,this is scalar
3) Use this to simplify and check if it is a scalar.
What is equilibrium?
An object is in equilbrium if it has a resultant force of zero and is not accelerating
How do we use a free body diagram to show that forces are in equilibrium?
Can construct a closed triangle of forces
What is a free body diagram?
A diagram that shows all forces that act on a point object.
How to calculate moments?
Moment = force x perpendicular distance from pivot
What is the principle of moments?
Sum of clockwise moments = sum of anticlockwise moments
Where is the centre of mass?
Halfway along an object of uniform mass ( e.g. 1.5m along a 3m beam )
What is the centre of mass?
The point on the object where the weight force acts
OR
The point in a body around which the resultant torque due to the pull of gravity is zero.
What is a couple?
A pair of forces that provide a turning effect but no transational movement. They act in opposite directions but are parallel, but do not act along the same line.
What is the resultant vector?
The vector found from combining vertical and horizontal vectors.
What are resolving vectors?
Resolving factors found by breaking down a vector into vertical and horizontal components.
