INTRO TO MECHANICS Flashcards
Define a Scalar Quantity.
One that only has MAGNITUDE.
Define a Vector Quantity.
One that has both direction and magnitude.
What are the two ways to add vectors?
Using trigonometry.
By scale drawing having a scale. Drawing vectors tip to tip
Drawing resultant.
Measure length + angle.
How do you resolve vectors?
Horizontal component is Vcos@
Vertical component is Vsin@
What happens to a object in equilibrium with no resultant force?
It will remain stationary or will travel at uniform speed.
Conditions for 2 or 3 coplanar forces to be in equilibrium.
Total resultant force is zero.
When forces added together they form a closed triangle.
How to work out components on a inclined plane.
Component down the slope is Wsin@
Component perpendicular to the slope is Wcos@
Define moment.
The turning force.
Define size of moment.
The force multiplied by the perpendicular distance between the line of action of the force and the pivot.
Moment = Fd
Define the principle of moments.
In equilibrium, the sum of the clockwise moments about a point is equal to the sum of anticlockwise moments.
State two conditions for equilibrium.
Resultant force is zero.
Resultant moments about any point is zero.
Define Centre of gravity.
Where all weight appears to act in an object.
Define Centre of mass.
Point in an object where resultant moment is zero.
Describe Unstability.
Unstable when centre of mass moves easily beyond pivot point so will continue to turn when force is removed.
For greater stability you can widen the base or lower the centre of mass.
