Mechanics and Materials (1): Forces in Equilibrium Flashcards
What is the definition of a vector?
A physical quantity that has direction as well as magnitude
What is the definition of a scalar?
A physical quantity that is not directional
What is the definition of displacement?
The distance in a given direction
What is the definition of velocity?
The speed in a given direction
What is the equation for the total displacement of a multistep journey?
Total displacement vector = the sum of the individual displacement vectors
What has to be true to add any two vectors?
They have to be of the same type
When answering a displacement question what two values do you need to include?
The magnitude and angle of displacement
What is the general equation that shows the magnitude of the resultant forces between two forces, F1 and F2, and the angle between the resultant and F1?
- The magnitude of the resultant force, F = (F1^2 + F2^2)^1/2
- The angle is given by tan(theta) = F2/F1
What is true when an object is equilibrium?
If the two forces acting on the object are equal but opposite/ the resultant is 0N/ the two forces are balanced
In what two instances can equilibrium occur?
- stationary object
- object moving at a constant velocity
For an object laying flat on a surface what is the reaction force equal to?
The weight of the object acting downwards
In what scenario is the resultant zero when three forces are applied to an object?
- If the resultant of any two of the forces is equal and opposite to the third force
To check this:
- Resolve each force along the same parallel and perpendicular lines
- Balance the components a long each line
If you have a suspended weight that is attached to ropes of different tensions what are the first steps you need to do?
You need to resolve vertically and horizontally and set ma = 0
What is a positive and negative of using a a longer spanner when loosening a nut on a bicycle?
Positive - less force is required to loosen the nut
Negative - If the spanner is too long then it could snap if too much force is applied to it
What is the definition of the moment of a force at any point?
The force x the perpendicular distance from the line of action of the force to the pivot