AQA A-LEVEL PHYSICS 7408/2 PAPER 2
MERGED LATEST 2025-2026 EXAM UPDATE
QUESTION AND ANSWERS
Describe the analysis of results for the Charles' law required practical. -
Answer-Plot a graph of volume against temperature. If the temperature
is plotted in Kelvin, then you should note that the graph is a straight line
THROUGH THE ORIGIN, confirming the concept of absolute zero. A
straight line relationship also proves the direct proportionality of volume
and temperature for a constant pressure. If the temperature is in degrees
C, then the data can be extrapolated to prove that absolute zero is -
273.15 degrees C.
Give a possible improvement to the method for the Charles' law
required practical. - Answer-Use a capillary tube rather than a gas
syringe, because it is thinner and therefore it is easier to measure a
change in height. Note that since it is a cylinder, the change in height is
directly proportional to the change in volume.
Describe how our understanding of gases has changed over time. -
Answer-Ideas that matter is made up of atoms have existed since
antiquity. In the 1600s and 1700s, Boyle's law, the pressure law and
Charles' law were discovered in turn. Kinetic theory and Brownian
motion were independently developed, and then unified by Einstein in
1905.
What is meant by a force field? - Answer-a region where a body
experiences a non-contact force
, Give some examples of fields in physics. - Answer-gravitational,
electric and magnetic fields
Is a force field a scalar or a vector? - Answer-a vector, because it has a
direction
What are two properties of fields? - Answer-fields can be uniform or
radial
What is meant by a uniform field? - Answer-one in which the field
strength is the same at all points (the field vectors are parallel to each
other, just like the electric field between charged plates)
What is meant by a radial field? - Answer-one in which the force
vectors point to the centre of a circle; each of them is perpendicular to
the tangent to the circle; just like the gravitational field of planet Earth
Is a gravitational field radial or uniform? - Answer-radial, but on a very
local scale the curvature of the Earth is such that the force vectors appear
to be effectively parallel, making the field more uniform
Newton's law of universal gravitation - Answer-The force between two
masses is directly proportional to the product of their masses and
inversely proportional to the square of the distance between them.
F = (GmM)/r^2
,F = gravitational force, N
G = gravitational constant, 6.67 x 10^-11 Nm^2kg^-2
m = mass of the object in orbit, kg
M = mass of the object being orbited, kg
r = distance between the centres of masses of the orbit, m
What is the gravitational constant, G? - Answer-a constant used in
Newton's law of universal gravitation which is a very small standard
form number (6.67 x 10^-11 Nm^2kg^-2) that reflects the fact that the
gravitational force is extremely weak
What is the unit for the gravitational constant? - Answer-Nm^2kg^-2;
this can be found by dimensional analysis (in which by convention we
use square brackets around the units), and note that by convention, even
though N is not an SI base unit, we tend to leave the unit in the above
form
What does r represent in Newton's law of universal gravitation? -
Answer-the distance between the centres of mass of the objects
What type of law is Newton's law of gravitation an example of? -
Answer-an inverse square law
What do we have to be careful with when determining r for use in
Newton's law of gravitation? - Answer-we may need to add/subtract the
radii of the planets (especially when the orbits eg of satellites are
, sufficiently low that the radii make a difference) and so you should read
the question carefully!
How does w = mg connect with F = GmM / r^2 ? - Answer-if you use
the mass of the Earth, the radius of the Earth and the mass of an object
on Earth's surface with the universal gravitation law, the answer would
be the same as if you were to simply multiply the mass of the object by
little g
What does it mean for the resultant gravitational field between two
planets to be 0 at a given point? - Answer-the value of the gravitational
field strength g = GM/r^2 for both planets are equal to each other at that
point
What can be said about an object in orbit? - Answer-The centripetal
force acting on the object is equal to the gravitational force between the
object and the planet it is orbiting. So we can write mv^2/r = GmM/r^2
By equating centripetal force and gravitational force (for an object in
orbit), give the non-given equation which relates the orbital velocity to
the gravitational constant, the mass of the planet being orbited and the
distance between them (note that this does NOT depend on the mass of
the object in orbit, so a tennis ball would orbit with the same speed as
the ISS if it were at the same height) - Answer-v = √(GM/r)
How might you go about estimating the answer to a gravitational fields
question? - Answer-consider the orders of magnitude only, eliminating
the mantissas (numbers in front of the powers of 10)
MERGED LATEST 2025-2026 EXAM UPDATE
QUESTION AND ANSWERS
Describe the analysis of results for the Charles' law required practical. -
Answer-Plot a graph of volume against temperature. If the temperature
is plotted in Kelvin, then you should note that the graph is a straight line
THROUGH THE ORIGIN, confirming the concept of absolute zero. A
straight line relationship also proves the direct proportionality of volume
and temperature for a constant pressure. If the temperature is in degrees
C, then the data can be extrapolated to prove that absolute zero is -
273.15 degrees C.
Give a possible improvement to the method for the Charles' law
required practical. - Answer-Use a capillary tube rather than a gas
syringe, because it is thinner and therefore it is easier to measure a
change in height. Note that since it is a cylinder, the change in height is
directly proportional to the change in volume.
Describe how our understanding of gases has changed over time. -
Answer-Ideas that matter is made up of atoms have existed since
antiquity. In the 1600s and 1700s, Boyle's law, the pressure law and
Charles' law were discovered in turn. Kinetic theory and Brownian
motion were independently developed, and then unified by Einstein in
1905.
What is meant by a force field? - Answer-a region where a body
experiences a non-contact force
, Give some examples of fields in physics. - Answer-gravitational,
electric and magnetic fields
Is a force field a scalar or a vector? - Answer-a vector, because it has a
direction
What are two properties of fields? - Answer-fields can be uniform or
radial
What is meant by a uniform field? - Answer-one in which the field
strength is the same at all points (the field vectors are parallel to each
other, just like the electric field between charged plates)
What is meant by a radial field? - Answer-one in which the force
vectors point to the centre of a circle; each of them is perpendicular to
the tangent to the circle; just like the gravitational field of planet Earth
Is a gravitational field radial or uniform? - Answer-radial, but on a very
local scale the curvature of the Earth is such that the force vectors appear
to be effectively parallel, making the field more uniform
Newton's law of universal gravitation - Answer-The force between two
masses is directly proportional to the product of their masses and
inversely proportional to the square of the distance between them.
F = (GmM)/r^2
,F = gravitational force, N
G = gravitational constant, 6.67 x 10^-11 Nm^2kg^-2
m = mass of the object in orbit, kg
M = mass of the object being orbited, kg
r = distance between the centres of masses of the orbit, m
What is the gravitational constant, G? - Answer-a constant used in
Newton's law of universal gravitation which is a very small standard
form number (6.67 x 10^-11 Nm^2kg^-2) that reflects the fact that the
gravitational force is extremely weak
What is the unit for the gravitational constant? - Answer-Nm^2kg^-2;
this can be found by dimensional analysis (in which by convention we
use square brackets around the units), and note that by convention, even
though N is not an SI base unit, we tend to leave the unit in the above
form
What does r represent in Newton's law of universal gravitation? -
Answer-the distance between the centres of mass of the objects
What type of law is Newton's law of gravitation an example of? -
Answer-an inverse square law
What do we have to be careful with when determining r for use in
Newton's law of gravitation? - Answer-we may need to add/subtract the
radii of the planets (especially when the orbits eg of satellites are
, sufficiently low that the radii make a difference) and so you should read
the question carefully!
How does w = mg connect with F = GmM / r^2 ? - Answer-if you use
the mass of the Earth, the radius of the Earth and the mass of an object
on Earth's surface with the universal gravitation law, the answer would
be the same as if you were to simply multiply the mass of the object by
little g
What does it mean for the resultant gravitational field between two
planets to be 0 at a given point? - Answer-the value of the gravitational
field strength g = GM/r^2 for both planets are equal to each other at that
point
What can be said about an object in orbit? - Answer-The centripetal
force acting on the object is equal to the gravitational force between the
object and the planet it is orbiting. So we can write mv^2/r = GmM/r^2
By equating centripetal force and gravitational force (for an object in
orbit), give the non-given equation which relates the orbital velocity to
the gravitational constant, the mass of the planet being orbited and the
distance between them (note that this does NOT depend on the mass of
the object in orbit, so a tennis ball would orbit with the same speed as
the ISS if it were at the same height) - Answer-v = √(GM/r)
How might you go about estimating the answer to a gravitational fields
question? - Answer-consider the orders of magnitude only, eliminating
the mantissas (numbers in front of the powers of 10)
