AQA Physics Paper 2 2023 – Q’s & A’s
force - ✔️ - this can change something's speed, direction, or shape
- it can be push/repulsive or pull/attractive
vector - ✔️ a quantity with magnitude (size) AND direction
scalar - ✔️ a quantity with magnitude (size) but NOT direction
examples of vectors - ✔️ force, weight, velocity, acceleration, displacement
examples of scalars - ✔️ distance, mass, speed, energy, time
contact forces - ✔️ occur when an object is supported by or strikes another
object e.g. friction
non-contact forces - ✔️ the objects don't physically come into contact, e.g.
gravity, magnetic force
mass - ✔️ the measure of the amount of matter that anything (including
people) are made up of (this is a scalar)
weight - ✔️ the measure of the force on an object due to gravity (gravity has
a direction, towards the centre of the Earth, so this is a vector)
the Earth's gravity - ✔️ 9.81m/s² (approx.) - it is in m/s² because gravity
refers to the acceleration that is put on objects as they are pulled in
weight - ✔️ = mass X gravity (can be rearranged) - (also, gravity will always
be 9.81 on Earth (above))
gravity ideas on the moon and Earth - ✔️ - the gravity of the moon is less
than on Earth as the moon has less mass than the Earth
- one would weigh less on the moon than on Earth, but still have the same
mass
- there is no air resistance on the moon as there is no air, so two objects
dropped simultaneously, regardless of their weight/mass, would hit the
ground simultaneously, as there is no force working against gravity
,resultant forces - ✔️ the eventual force of two forces acting on one object
- if the forces are acting in the same/opposite directions, just add/subtract
- if they are acting at an angle to each other:
- draw a scale drawing of all the forces acting
- measure the distance from tip to tip of the forces; thats the resultant force
- use a protractor to find a bearing for the force, as force is a vector (so has to
have direction too)
resolving forces - ✔️ to resolve a force you want to split it into its horizontal
and vertical components:
- draw a diagram with the info you have
- label the sides
- find one component using trig
- find the other component using trig
work done - ✔️ the transfer of energy in order to move something - it is a
form of energy, and so is a scalar, as energy is also a scalar
work (Nm or J) - ✔️ = force (N) X displacement (m) (can be rearranged)
1 Nm (newtonmetre) - ✔️ = 1 J (joule)
F∝e → F=ke - ✔️ the extension of the spring is directly proportional to the
force exerted on it
extension (e) - ✔️ the difference between the original length and the
extended length
spring constant (k) - ✔️ how much the spring stretches with a given force
Hooke's law - ✔️ states that the strain in a solid (e.g. a spring) is
proportional to the applied stress (within the elastic limit of that solid)
Ee (elastic energy) - ✔️ = 0.5ke²
(the energy topic is covered in more detail in paper 1)
, moment - ✔️ the moment of a force is the turning effect it has on an object
connected to a pivot - for an object with a pivot to be in equilibrium the
moments must be equal
M (Nm) - ✔️ = F (N) X d (m) (the unit for moments is Nm and not J as a
moment is a turning effect, not an energy)
gears - ✔️ use the principle of moments to transmit a turning effect -
different sized gears can be used to change a moment - a gear turns in the
opposite direction to the gear it is attached to - gear = cog
centre of mass - ✔️ the point in an object at which its mass can be thought
of as being concentrated
pressure - ✔️ the amount of force exerted per unit squared of the area of
the object
fluids - ✔️ substances that flow because their particles are able to move
around - fluids include liquids and gases
fluid pressure - ✔️ p = f ÷ a
(pressure in Pa) = (force perp. to a surface in N) ÷ (area of that surface in m²)
1 Pa - ✔️ = 1N/m²
liquid pressure - ✔️ this depends also on depth and density, as:
1. the more dense the liquid is, the more collisions happen
2. the more depth there is, the more particles there are above any given point,
so the pressure from above increases as we go deeper
so:
p=hXρXg
(pressure in Pa) = (depth/height in m) X (density in kg/m³) X (gravitational
field strength in N/kg (9.81 on Earth))
atmosphere - ✔️ the layer of gas surrounding the Earth
atmospheric pressure - ✔️ this decreases as altitude increases as there are
less particles at higher altitudes so the pressure is less
force - ✔️ - this can change something's speed, direction, or shape
- it can be push/repulsive or pull/attractive
vector - ✔️ a quantity with magnitude (size) AND direction
scalar - ✔️ a quantity with magnitude (size) but NOT direction
examples of vectors - ✔️ force, weight, velocity, acceleration, displacement
examples of scalars - ✔️ distance, mass, speed, energy, time
contact forces - ✔️ occur when an object is supported by or strikes another
object e.g. friction
non-contact forces - ✔️ the objects don't physically come into contact, e.g.
gravity, magnetic force
mass - ✔️ the measure of the amount of matter that anything (including
people) are made up of (this is a scalar)
weight - ✔️ the measure of the force on an object due to gravity (gravity has
a direction, towards the centre of the Earth, so this is a vector)
the Earth's gravity - ✔️ 9.81m/s² (approx.) - it is in m/s² because gravity
refers to the acceleration that is put on objects as they are pulled in
weight - ✔️ = mass X gravity (can be rearranged) - (also, gravity will always
be 9.81 on Earth (above))
gravity ideas on the moon and Earth - ✔️ - the gravity of the moon is less
than on Earth as the moon has less mass than the Earth
- one would weigh less on the moon than on Earth, but still have the same
mass
- there is no air resistance on the moon as there is no air, so two objects
dropped simultaneously, regardless of their weight/mass, would hit the
ground simultaneously, as there is no force working against gravity
,resultant forces - ✔️ the eventual force of two forces acting on one object
- if the forces are acting in the same/opposite directions, just add/subtract
- if they are acting at an angle to each other:
- draw a scale drawing of all the forces acting
- measure the distance from tip to tip of the forces; thats the resultant force
- use a protractor to find a bearing for the force, as force is a vector (so has to
have direction too)
resolving forces - ✔️ to resolve a force you want to split it into its horizontal
and vertical components:
- draw a diagram with the info you have
- label the sides
- find one component using trig
- find the other component using trig
work done - ✔️ the transfer of energy in order to move something - it is a
form of energy, and so is a scalar, as energy is also a scalar
work (Nm or J) - ✔️ = force (N) X displacement (m) (can be rearranged)
1 Nm (newtonmetre) - ✔️ = 1 J (joule)
F∝e → F=ke - ✔️ the extension of the spring is directly proportional to the
force exerted on it
extension (e) - ✔️ the difference between the original length and the
extended length
spring constant (k) - ✔️ how much the spring stretches with a given force
Hooke's law - ✔️ states that the strain in a solid (e.g. a spring) is
proportional to the applied stress (within the elastic limit of that solid)
Ee (elastic energy) - ✔️ = 0.5ke²
(the energy topic is covered in more detail in paper 1)
, moment - ✔️ the moment of a force is the turning effect it has on an object
connected to a pivot - for an object with a pivot to be in equilibrium the
moments must be equal
M (Nm) - ✔️ = F (N) X d (m) (the unit for moments is Nm and not J as a
moment is a turning effect, not an energy)
gears - ✔️ use the principle of moments to transmit a turning effect -
different sized gears can be used to change a moment - a gear turns in the
opposite direction to the gear it is attached to - gear = cog
centre of mass - ✔️ the point in an object at which its mass can be thought
of as being concentrated
pressure - ✔️ the amount of force exerted per unit squared of the area of
the object
fluids - ✔️ substances that flow because their particles are able to move
around - fluids include liquids and gases
fluid pressure - ✔️ p = f ÷ a
(pressure in Pa) = (force perp. to a surface in N) ÷ (area of that surface in m²)
1 Pa - ✔️ = 1N/m²
liquid pressure - ✔️ this depends also on depth and density, as:
1. the more dense the liquid is, the more collisions happen
2. the more depth there is, the more particles there are above any given point,
so the pressure from above increases as we go deeper
so:
p=hXρXg
(pressure in Pa) = (depth/height in m) X (density in kg/m³) X (gravitational
field strength in N/kg (9.81 on Earth))
atmosphere - ✔️ the layer of gas surrounding the Earth
atmospheric pressure - ✔️ this decreases as altitude increases as there are
less particles at higher altitudes so the pressure is less
