FORCES Flashcards
What is a vector quantity?
Direction and magnitude
What is a scalar quantity?
Magnitude only
How are vector quantities usually represented by?
An arrow showing direction and length shows magnitude
What are some examples of vector quantities?
Force
Velocity
Displacement
Acceleration
Momentum
What are some examples of scalar quantities?
Speed
Distance
Mass
Temperature
Time
What are contact forces?
Have to be touching for a force to act (e.g. friction, air resistance)
What are non-contact forces?
Don’t have to be touching for force to act (e.g. gravitational force, electrostatic force)
What is an interaction pair?
A pair of forces that are equal and opposite and act on two interacting objects
What is mass?
The amount of stuff in an object
What is weight?
The force acting on an object due to gravity
What does the weight of an object depend on?
The strength of the gravitational field at the location of the object
What is the relationship between mass and weight?
They are directly proportional
What does a free-body diagram show
All the forces acting on an isolated object
Size of arrows shows the relative magnitude of the forces
Also shows direction
What is the resultant force of an object?
Add forces going in the same direction
Subtract ones going in different direction
(along the same line)
What happens when a force acts on an object?
Work is done to move the object so energy is transferred from one store to another
How do you convert joules to newton metres?
1J = 1Nm
How do you calculate resultant forces using scale drawings?
Draw forces (North however many cm then East)
Calculate the line (triangle) between them starting from where the force started
What happens when all the forces acting on an object equal 0?
The object is in equilibrium
How do you find the single force of a force acting at an awkward angle?
Draw the components at right angles to each other
Horizontal and vertical component then work out line connecting them
What can an object do if it has been elastically deformed?
It can go back to its original shape and length after the force has been removed
What happens when work is done and an object is stretched or compressed (force wise)?
Energy is transferred to the elastic potential energy store
What forces need to be applied for an object to stretch, compress or bend?
More than one force acting on the object or otherwise it would just move in the direction the force is pushing/pulling
What is the relationship between extension and force applied/load?
They are directly proportional
What does the spring constant of a spring depend on?
The stiffer the material the greater the spring constant
What is the limit of proportionality of a spring?
When the force is great enough (limit to amount) that it is not directly proportional to the extension anymore
What is a moment?
The turning effect of a force
What can increase moment?
A larger force or a longer distance
What will happen if the total anticlockwise moment is equal to the total clockwise moment?
The object is balanced and won’t turn
What do levers do?
They increase the distance from the pivot at which the force is applied so less force is needed to get the same moment