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
What is the equation that links pressure, force normal to a surface and area of that surface?
P = F A
What is the cause of pressure in fluids
The pressure in a liquid is due to the weight. The force acts towards the centre of the planet and is measured in newtons (N). of the column of water above. Since the particles in a liquid are tightly packed, this pressure acts in all directions.
What is the equation linking pressure, height of the column, density of the liquid and gravitational field strength?
Pressure due to the weight of a liquid of constant density is given by p=ρgh p = ρ g h , where p is the pressure, h is the depth of the liquid, ρ is the density of the liquid, and g is the acceleration due to gravity
What factors affect pressure in a column at a particular point?
The pressure at a point in a liquid depends on:
density of the liquid.
acceleration due to gravity.
depth below the free surface
The pressure at a point in a liquid depends on:
density of the liquid.
acceleration due to gravity.
depth below the free surface.
Explain why these factors affect the pressure
Density of the liquid affects pressure because when density increases pressure also increases- directly proportional to one another
Acceleration due to gravity affects pressure because Gravity’s influence on fluid pressure is that it causes the fluid body to move in the opposite direction of its net acceleration.
Depth below the free surface affects pressure because the deeper the object is placed in the fluid, the more pressure it experiences. This is because is the weight of the fluid above it. The more dense the fluid above it, the more pressure is exerted on the object that is submerged, due to the weight of the fluid.
explain which factors influence whether an object floats or sinks
Density is a measure of how heavy something is compared to its size. If an object is more dense than water it will sink when placed in water, and if it is less dense than water it will float.
what is atmospheric pressure
Air molecules colliding with a surface cause atmospheric pressure. Atmospheric pressure at sea level is about 101,000 Pa (101 kPa) but just 27,000 Pa (27 kPa) at the cruising altitude of a passenger plane. Atmospheric pressure decreases as the height of a surface above ground level increases.
why does atmospheric pressure vary with height above a surface
pressure decreases with increasing altitude. This is because as the altitude above the surface increases there are fewer air molecules therefore the mass decreases - decreasing the pressure
what factors will affect the speed a person can walk
the force acting on the object, the mass of the object, the surface it is moving on, and the presence of friction or other resistive forces.
what is the equation linking distance travelled, speed and time
Speed = distance/time
what is the difference between speed and velocity
Speed is the time rate at which an object is moving along a path, while velocity is the rate and direction of an object’s movement. Put another way, speed is a scalar value, while velocity is a vector
describe what happens to the velocity of an object moving in a circle at a constant speed
An object moving in a circular orbit at a constant speed has a changing velocity
What does a distance time graph represent
A distance-time graph shows how the distance and speed of an object changes with time.
How can you find the speed from a distance time graph
In a distance-time graph, the gradient of the line is equal to the speed of the object. The greater the gradient (and the steeper the line) the faster the object is moving.
How can you tell if an object is moving at a faster speed in a distance time graph
The steeper the line (and the greater the gradient) the faster the object is moving.
what is the equation linking acceleration change in velocity and time
a = v/t
what is the equation for uniform acceleration
v=u + at
Units for acceleration, initial velocity and final velocity
final velocity (v) is measured in metres per second (m/s) initial velocity (u) is measured in metres per second (m/s) acceleration (a) is measured in metres per second squared (m/s2)
