CIE A Levels Physics (9702)
CIE A Levels Physics (9702)
Grade Booster – A2 – FAQs
Frequently Asked Questions
Circular Motion
1. Define the radian.
• The radian is a unit of measurement for an angle, where one radian is defined as the angle
subtended at the center of a circle by an arc that is equal in length to the radius of the
circle.
• The Radian is the unit for the ratio of the circumference to the radius of the circle.
2. Why one complete revolution is equivalent to an angular displacement of 𝟐𝝅 radians.
One complete revolution of a circle is equivalent to an angular displacement of 2𝜋 radians
because the circumference of a circle is 2𝜋 times the radius. Therefore, one complete revolution
corresponds to an angle of 2𝜋 radians.
3. Explain what is meant by angular speed.
Angular speed refers to the rate of change of the angle of an object moving in circular motion,
measured in radians per second.
Gravitational Fields
1. Explain what is meant by gravitational field.
A gravitational field is a region in space where a mass experiences a force due to the
presence of another mass. It is a vector field, meaning that it has both a magnitude (the
strength of the field) and a direction (towards the source of the field).
2. Explain why the normal reaction on a mass will have different values at the equator and at
the poles.
𝐺𝑀𝑚
𝑚𝑟𝜔 2 = −𝑁
𝑅2
𝐺𝑀𝑚
𝑁= − 𝑚𝑟𝜔2
𝑅2
1
STEM Ninja
,CIE A Levels Physics (9702)
The value of 𝑟 in expression 𝑚𝑟𝜔2 decreases from equator to poles and becomes zero at poles
so the mass at poles is not in circular motion due to zero centripetal force. Hence normal reaction
is greater at poles than equator.
3. Define gravitational field strength.
Gravitational field strength is defined as the force per unit mass experienced by a small test mass
placed in a gravitational field. Its SI unit is Newtons per kilogram (N/kg).
4. Define gravitational potential at a point.
Gravitational potential at a point is defined as the amount of work done per unit mass in bringing
a small test mass from infinity to that point in the gravitational field. Its SI unit is joules per kilogram
(J/kg).
5. State what is meant by a field of force.
A field of force is a region in space where a force exists and is exerted on objects that are present
in that region.
6. Gravitational fields and electric fields are two examples of fields of force. State one
similarity and one difference between these two fields of force.
• Similarity: They both follow the inverse-square law, meaning that the strength of the field
decreases with the square of the distance from the source.
• Difference: Gravitational fields are always attractive, while electric fields can be either
attractive or repulsive.
7. State Newton’s law of gravitation.
Newton's law of gravitation states that every particle in the universe attracts every other particle
with a force that is directly proportional to the product of their masses and inversely proportional
to the square of the distance between them.
8. Explain what is meant by Geostationary orbit.
A geostationary orbit is an orbit around the Earth at a fixed altitude and in the same direction as
the Earth's rotation, such that the orbiting object remains fixed above a particular location on the
Earth's surface.
Thermal Physics: Temperature, Thermodynamics, Ideal Gases
1. Explain what is meant by Brownian motion.
Brownian motion is the random, erratic movement of microscopic particles suspended in a fluid,
caused by collisions with molecules of the surrounding fluid.
2
STEM Ninja
, CIE A Levels Physics (9702)
2. Suggest and explain why Brownian motion provides evidence for movement of molecules
as is assumed in the kinetic theory of gases.
The abrupt changes of paths of smoke particles are due to the uneven bombardment of invisible
air particles from different directions and at different times. This indicates the random motion of
molecules of gases.
3. State what is meant by a mole.
A mole is a unit of measurement in chemistry that represents a certain number of particles.
Specifically, one mole of a substance contains Avogadro's constant (6.02 × 10^23) particles.
4. One assumption of the kinetic theory of gases is that the gas molecules behave as if they
are hard elastic identical spheres. State two other assumptions of kinetic theory of gases.
• The gas molecules are in constant random motion, and their velocity is proportional to the
temperature of the gas.
• The gas molecules do not interact with each other except during collisions, which are
perfectly elastic.
5. State what is meant by internal energy of a substance.
The internal energy of a substance is the sum of the kinetic and potential energies of its
particles. It represents the total energy of the particles that make up a substance, including
their random motion and interactions with each other.
6.
a. Describe apparatus that demonstrates Brownian motion. Include a diagram.
b. Describe the observations made using the apparatus.
Random motion of smoke particles shows the random motion of gas or air particles
continuous motion of smoke particles provide evidence for the perpetual motion of gas or
air particles
c. State and explain two conclusions about the properties of molecules of a gas that
follow from observations in that experiment.
• Random motion of smoke particles shows the random motion of gas or air
particles.
• Continuous motion of smoke particles provided evidence for the perpetual motion
of gas or air particles.
3
STEM Ninja
CIE A Levels Physics (9702)
Grade Booster – A2 – FAQs
Frequently Asked Questions
Circular Motion
1. Define the radian.
• The radian is a unit of measurement for an angle, where one radian is defined as the angle
subtended at the center of a circle by an arc that is equal in length to the radius of the
circle.
• The Radian is the unit for the ratio of the circumference to the radius of the circle.
2. Why one complete revolution is equivalent to an angular displacement of 𝟐𝝅 radians.
One complete revolution of a circle is equivalent to an angular displacement of 2𝜋 radians
because the circumference of a circle is 2𝜋 times the radius. Therefore, one complete revolution
corresponds to an angle of 2𝜋 radians.
3. Explain what is meant by angular speed.
Angular speed refers to the rate of change of the angle of an object moving in circular motion,
measured in radians per second.
Gravitational Fields
1. Explain what is meant by gravitational field.
A gravitational field is a region in space where a mass experiences a force due to the
presence of another mass. It is a vector field, meaning that it has both a magnitude (the
strength of the field) and a direction (towards the source of the field).
2. Explain why the normal reaction on a mass will have different values at the equator and at
the poles.
𝐺𝑀𝑚
𝑚𝑟𝜔 2 = −𝑁
𝑅2
𝐺𝑀𝑚
𝑁= − 𝑚𝑟𝜔2
𝑅2
1
STEM Ninja
,CIE A Levels Physics (9702)
The value of 𝑟 in expression 𝑚𝑟𝜔2 decreases from equator to poles and becomes zero at poles
so the mass at poles is not in circular motion due to zero centripetal force. Hence normal reaction
is greater at poles than equator.
3. Define gravitational field strength.
Gravitational field strength is defined as the force per unit mass experienced by a small test mass
placed in a gravitational field. Its SI unit is Newtons per kilogram (N/kg).
4. Define gravitational potential at a point.
Gravitational potential at a point is defined as the amount of work done per unit mass in bringing
a small test mass from infinity to that point in the gravitational field. Its SI unit is joules per kilogram
(J/kg).
5. State what is meant by a field of force.
A field of force is a region in space where a force exists and is exerted on objects that are present
in that region.
6. Gravitational fields and electric fields are two examples of fields of force. State one
similarity and one difference between these two fields of force.
• Similarity: They both follow the inverse-square law, meaning that the strength of the field
decreases with the square of the distance from the source.
• Difference: Gravitational fields are always attractive, while electric fields can be either
attractive or repulsive.
7. State Newton’s law of gravitation.
Newton's law of gravitation states that every particle in the universe attracts every other particle
with a force that is directly proportional to the product of their masses and inversely proportional
to the square of the distance between them.
8. Explain what is meant by Geostationary orbit.
A geostationary orbit is an orbit around the Earth at a fixed altitude and in the same direction as
the Earth's rotation, such that the orbiting object remains fixed above a particular location on the
Earth's surface.
Thermal Physics: Temperature, Thermodynamics, Ideal Gases
1. Explain what is meant by Brownian motion.
Brownian motion is the random, erratic movement of microscopic particles suspended in a fluid,
caused by collisions with molecules of the surrounding fluid.
2
STEM Ninja
, CIE A Levels Physics (9702)
2. Suggest and explain why Brownian motion provides evidence for movement of molecules
as is assumed in the kinetic theory of gases.
The abrupt changes of paths of smoke particles are due to the uneven bombardment of invisible
air particles from different directions and at different times. This indicates the random motion of
molecules of gases.
3. State what is meant by a mole.
A mole is a unit of measurement in chemistry that represents a certain number of particles.
Specifically, one mole of a substance contains Avogadro's constant (6.02 × 10^23) particles.
4. One assumption of the kinetic theory of gases is that the gas molecules behave as if they
are hard elastic identical spheres. State two other assumptions of kinetic theory of gases.
• The gas molecules are in constant random motion, and their velocity is proportional to the
temperature of the gas.
• The gas molecules do not interact with each other except during collisions, which are
perfectly elastic.
5. State what is meant by internal energy of a substance.
The internal energy of a substance is the sum of the kinetic and potential energies of its
particles. It represents the total energy of the particles that make up a substance, including
their random motion and interactions with each other.
6.
a. Describe apparatus that demonstrates Brownian motion. Include a diagram.
b. Describe the observations made using the apparatus.
Random motion of smoke particles shows the random motion of gas or air particles
continuous motion of smoke particles provide evidence for the perpetual motion of gas or
air particles
c. State and explain two conclusions about the properties of molecules of a gas that
follow from observations in that experiment.
• Random motion of smoke particles shows the random motion of gas or air
particles.
• Continuous motion of smoke particles provided evidence for the perpetual motion
of gas or air particles.
3
STEM Ninja
