Assessment 2: P8-P11 Flashcards
What is a fluid
A substance that can flow (liquids and gases)
Describe upthrust
It is a force that pushes things upwards
Describe the difference between vector and scalar quantities
Vector quantities have a size and direction whereas scalar quantities only have a size
Give an example of a scalar and a vector quantity
Scalar: energy
Vector: displacement
What do the length and direction of arrows represent for forces
Their length represent the magnitude of the force, while their arrowheads represent the direction where the force acts.
List the different types of forces, e.g. friction.
Air resistance
Drag
Water resistance
Magnetism
Gravity
Elastic
Electrostatic
What is the equation that links weight, mass and gravitational field strength
𝑊 = 𝑚 𝑔
definition for a resultant force
the total amount of force acting on the object or body along with the direction of the body.
Describe the relationship between mass and weight
Weight is the measure of the force of gravity on an object’s mass, while mass is the measure of how much matter there is in an object. The proportionality between weight and mass lead to the following relationship: W = m x g. W: Weight (in newton) m: mass (in kilogram)
Where does the weight act for an object?
The objects center of mass
Give some examples of balanced and m unbalanced forces.
Balanced force examples: A car that continues movies at the same speed, an object floating on water, a person standing still.
Unbalanced force examples: A vehicle accelerating, a fruit falling from a tree, a moving train slowing down before stopping.
What is the equation linking work done, distance and force?
Work = Force × Distance
What is the difference between displacement and distance?
Distance is the length of the path taken by an object whereas displacement is simply the distance between where the object started and where it ended up.
Write the units and symbols for the following:
work done:
force:
distance:
Work done: Joules= J
Force : Newtons=N
Distance : metres= m
How much work is done on a stationary box that is moved across a carpet by a person? The box weighs 5N and it is moved 50cm
Force= 5N
Displacement= 50cm (convert to metres) =0.5m
Work done = Force x displacement/distance
Work done = 5 x 0.5
Work done = 2.5 J
How many forces are required to stretch an elastic band and why?
1.two forces are involved, acting inwards onto the object; we call these forces “compression forces”.
- Stretching a blob of blu-tac or a rubber band: two forces are involved, acting outwards from the object; we call these forces “tension forces”.
Describe the difference between elastic deformation and inelastic deformation.
When an object is deformed, (stretched, bent or compressed), if it returns to its original shape once the forces are removed, it is an elastic deformation. If it does not return to its original shape it is an inelastic deformation.
Describe the relationship between extension of an elastic object and force applied.
extension of an elastic object is directly proportional to the force applied to it. In other words: • If the force applied is doubled, the extension doubles • If no force is applied, there is no extension The graph of force against extension is a straight line through the origin, which shows a linear relationship.
What is the equation that links force, spring constant a and extension?
As an equation, Hooke’s Law can be represented as F = kx, where F is the force we apply, k is the spring constant, and x is the extension of the material (typically in meters)
Write the units and symbols for the following:
force:
spring constant:
extension:
force (F) is measured in newtons (N)
spring constant (k) is measured in newtons per metre (N/m)
extension (e), or increase in length, is measured in metres (m)
What is spring constant
It is a measure of the stiffness of the spring
describe the difference between a linear and non linear relationship for force and extension
Hooke’s law is used to describe the relationship between force applied to an elastic object and the extension of the elastic object. It is a linear relationship, where force is directly proportional to the extension. If an object doesn’t obey Hooke’s law, there is a non-linear relationship between force and extension.
When an object is balanced, what is the relationship between the clockwise and anticlockwise moments?
If an object is balanced, the total clockwise moment about a point is equal to the total anticlockwise moment about the same point. This is called the Principle of Moments. Total clockwise moment = Total anticlockwise moment.
Would a long or a short spanner be more effective to loosen a nut?
A long spanner