Mechanics Goodnotes Recap Flashcards
Scalar Quantity?
A scalar quantity only has magnitude
Vector Quantity?
A vector quantity has a magnitude and a direction
Scalar Quantity Examples?
Examples of scalar quantities are speed, distance, time
Vector Quantity Examples?
Displacement, Velocity, Momentum
Scaled Diagrams?
Drawn from tip to tail and have length measured and the angle of the resultant vector found. Scaled diagrams are useful in finding the resultant vector of two vectors
Perpendicular Vectors?
If two vectors are perpendicular to each other it means trigonometry can be used to work out the angle between the vectors and the resultant vector
Resolving Vectors?
Knowing the resultant vector, a starting point is split into two components at right angles to each other. The two components, horizontal and vertical, are perpendicular to each other so form a right angled triangle which can have the known quantities re-arranged to find the unknown vector
Slope and Vectors?
If an object is on a slope, the angle of the slope is adjacent to the object, leading to weight of the object being perpendicular to the slope and meeting the weight of the slope at the same angle as the slopes incline
Perpendicular Vectors Relationship?
The relationship between 2 perpendicular vectors is the two vectors have no effect on each other. This means two directions can be dealt with separately and a force that affects 1 vector can be worked out without needing to consider the other vector
Forces and Vector quantities?
Forces are examples of vector quantities. This means the arrows of force in a free body diagram need to show direction and magnitude of forces acting on an object
Free-Body Diagrams?
Force diagram showing a single body that should include all forces acting on a body but not all the forces it exerts on the surroundings
Equilibrium?
While forces in an object are balanced with each other and cancel each other out
Force and equilibrium?
There are no resultant forces acting on an object in equilibrium. When there are forces acting on an object in equilibrium they need to have equal magnitude and opposite directions so they cancel each other out
Equilibrium and Velocity?
An object in equilibrium can be at rest or moving with a constant velocity
Equilibrium Problems?
Equilibrium problems can be solved by force vectors in a closed loop or by resolving forces in 2 perpendicular distances
Closed Loop in equilibrium?
Forces acting on an object in equilibrium form a closed loop when drawn tip to tail
Tip to tail equilibrium diagrams?
When 3 forces are tip to tail and create a closed loop it is referred to as a vector triangle. If a vector triangle involves more than 3 forces it is called a vector polygon
Resolving forces in equilibrium?
Resolving forces for objects in equilibrium is no different than forces in perpendicular components. If an object is in equilibrium the sum of the components in each direction equals zero. The components of each force in each direction is found with trigonometry
Force Boards?
A method of investigating equilibrium. They can be used to apply forces to an object and vary forces and the directions they act in find different conditions for equilibrium
Mass?
The amount of matter an object is composed of
Mass Relationships?
The greater an object’s mass the greater the resistance to change its velocity. The mass of an object doesn’t change if the strength of the gravitational field changes
Weight?
Weight is a force typically measured in Newtons (N) and is a force experienced by a mass due to a gravitational field. Weight can change depending on the size of the gravitational field
Weight Formula?
Weight = Mass x Gravitational Field Strength
W = Mg
Moment?
A turning effect of a force around a turning point
Moment factor?
The moment of a force depends on the size of the force and far the force is applied from the turning point
Moment Equation?
Moment of a Force = Size of a force x perpendicular distance between force and turning point
Principle of moments?
The principle of moments states for a body to be in equilibrium the sum of the clockwise moments about any point equals the sum of the anti-clockwise moments about the same point
Moments Factor?
If moments aren’t balanced the object will turn
Lever’s Purpose?
Levers are most useful where a large turning effect is required
Levers examples?
Spanner, wheelbarrows, scissors
Levers?
Levers increase the distance from the pivot and the applied force so less force is needed to generate the same moment
Effort Force in Levers?
An effort force otherwise input force acts against a load force otherwise output force by the means of a rigid object rotating around a pivot
Moments and Couples?
A couple doesn’t cause any resultant linear force but produces a turning effect called a moment. The size of the moment is dependant on the size of forces and the distances between them
Couple?
A couple is a pair of forces of equal size which acts parallel to each other in opposite directions
Moment Couple Equations?
Moment in Couple = Size of Force x perpendicular distance between line of action of forces
M = f x d
Centre of mass?
The single point that the whole weight of the objects acts through whatever the orientation of the object