A2 definitions

Question 1

State Newton’s 1st law of motion.

Answer 1

An object will move at constant velocity unless acted upon by an unbalanced force.

Question 2

State Newton’s 2nd Law of Motion.

Answer 2

The unbalanced force on an object is given by the rate of change of momentum.

Question 3

State Newton’s 3rd Law of Motion.

Answer 3

For every force there is an equal but opposite force.

Question 4

Define Linear Momentum.

Answer 4

The product of the mass and velocity of an object.

Question 5

The net or ‘resultant’ force on a body is equal to…

Answer 5

The rate of change of momentum.

Question 6

Define ‘impulse’

Answer 6

The change of momentum of an object.

Ft, where F is the force on an object t is the time for which it acts

Question 7

State the law of conservation of linear momentum.

Answer 7

For an isolated system, the total linear momentum in any direction is a constant.

Question 8

What is a ‘perfectly elastic’ collision?

Answer 8

A collision where kinetic energy is conserved.

Question 9

What is an ‘inelastic’ collision?

Answer 9

A collision where kinetic energy is NOT conserved.

Question 10

What is a radian?

Answer 10

A unit of angle where one full circle (360°) is equivalent to 2 radians.

Question 11

Define ‘gravitational field strength’

Answer 11

The gravitational force per unit mass.

The gravitational flux per unit perpendicular area.

Question 12

Define ‘gravitational potential’

Answer 12

The energy needed to bring a unit point mass from infinity to a given location.

Question 13

State Newton’s Law of Universal Gravitation.

Answer 13

The force (F) between two point masses (M1 and M2), a distance d apart is given by:

Question 14

Define ‘electric field strength’

Answer 14

The electric force per unit positive charge.

The electric flux per unit perpendicular area.

Question 15

Define ‘electric potential’

Answer 15

The energy needed to bring a unit point charge from infinity to a given location.

Question 16

What is a geostationary orbit?

Answer 16

The orbit of a satellite such that it is directly above a fixed point on the Earth.

Question 17

Define ‘internal energy’ of a system

Answer 17

The sum of the total kinetic energy and potential energy of a system.

Question 18

Pressure

Answer 18

The force per unit area

Question 19

Absolute zero

Answer 19

The temperature at which the internal energy of a system is a minimum. Equal to -273C or 0 K

Question 20

State Boyle’s Law.

Answer 20

For a system at constant temperature, the product of pressure and volume is a constant.
PV = constant.

Question 21

Define the mole.

Answer 21

The amount of a substance such that there are 6.02 x 10²³ basic particle present.

Question 22

What is Avogadro’s Constant?

Answer 22

6.02 x 10²³, the number of particles in a system when there is 1 mole present.

Question 23

Define ‘specific heat capacity’

Answer 23

The heat energy needed to raise 1kg of a substance by 1K.

Question 24

Define ‘latent heat of fusion’

Answer 24

The heat energy needed to change 1kg of a solid into a liquid.

Question 25

Define ‘latent heat of caporisation.’

Answer 25

The heat energy needed to change 1kg of a liquid into a gas.

Question 26

Define ‘the magnetic flux’ (e.g. through a loop)

Answer 26

BA, where A is the area of the loop and B is the magnetic flux density perpendicular to the plane in which the loop lies.

Question 27

Define ‘magnetic flux density’.

Answer 27

The magnetic flux density, B, is defined as F/IL, where F is the force on a conductor, L is the length of the conductor in the magnetic field, and I is the current in the conductor.

Question 28

Define the Tesla.

Answer 28

The magnetic field strength required to produce a 1N force on a wire of 1m length, with a 1A current flowing.

Question 29

Define the Weber.

Answer 29

The number of flux lines through a 1m² area in a field of strength 1T

Question 30

Define ‘magnetic flux linkage’.

Answer 30

The product of the magnetic flux and the number of turns in a coil.

Question 31

State Lenz’s Law

Answer 31

The induced EMF is in such a direction as to oppose the change producing it.

Question 32

State Faraday’s Law.

Answer 32

Induced EMF = minus the rate of change of magnetic flux linkage

Question 33

Define ‘capacitance.’

Answer 33

The stored charge in a capacitor per unit voltage across the plates.

Question 34

Define the capacitive ‘time constant’

Answer 34

Equals RC, where C is the capacitance of a capacitor and R is the resistance through which it is charging or discharging.
Also: the time taken for a capacitor to reduce its charge to 1/e (=approximately 37%) of its maximum value.

Question 35

Define the Farad.

Answer 35

The capacitance of a capacitor which stores a charge of 1C when a p.d. of 1V is applied across the plates.

Question 36

Define ‘displacement’ (in the context of SHM)

Answer 36

The distance moved, in a particular direction, from the rest point by an oscillating particle.

Question 37

State what is meant by the ‘amplitude’ of an object executing SHM.

Answer 37

The maximum distance the object moves from the rest point.

Question 38

Define the ‘period’ of an oscillation.

Answer 38

The time taken for one complete cycle to occur.

Question 39

Define the ‘frequency’ of an oscillation.

Answer 39

The number of cycles in 1 second.

Question 40

Define ‘phase difference’.

Answer 40

The amount by which two waves are out of step with each other. It is measured in degrees or radians.