the key words paper 1

Question 1

Power

Answer 1

Power is defined as the rate at which energy is transferred or at which work is done

Question 2

Current

Answer 2

Electric current is the rate of flow of electric charge

Question 3

Ohmic
conductor

Answer 3

The current through an ohmic conductor at constant temperature is
directly proportional to the potential difference across it

Question 4

National Grid

Answer 4

The National Grid is a system of cables and transformers linking power
stations to consumers

Question 5

Internal energy

Answer 5

Internal energy is the total kinetic and potential energy of all the particles that make up a system

Question 6

Specific heat capacity

Answer 6

The specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius

Question 7

Specific latent heat

Answer 7

The specific latent heat of a substance is the amount of energy required to change the state of one kilogram of the substance with no change in temperature

Question 8

Activity

Answer 8

Activity is the rate at which a source of unstable nuclei decays

Question 9

Count-rate

Answer 9

Count-rate is the number of decays recorded each second by a detector

Question 10

Half-life

Answer 10

The half-life of a radioactive isotope is the time it takes for the number of nuclei of the isotope in a sample to halve

or

The time it takes for the count-rate, or activity, from a sample containing the radioactive isotope to fall to half its initial level

Question 11

Contamination

Answer 11

Contamination is the unwanted presence of material containing radioactive atoms on other material

Question 12

Irradiation

Answer 12

Irradiation is the process of exposing an object to nuclear radiation

Question 13

Fission

Answer 13

Nuclear fission is the splitting of a large and unstable nucleus

Question 14

Fusion

Answer 14

Nuclear fusion is the joining of two light nuclei to form a heavier nucleus

Question 15

Joule

Answer 15

One joule of work is done when a force of one newton causes a displacement of one metre

Question 16

Moment

Answer 16

The turning effect of a force is called the moment of a force and is equal to the force multiplied by the perpendicular distance from the pivot to the line of action of the force

Question 17

Displacement

Answer 17

Displacement includes both the distance an object moves and the direction it moves from its start point

Question 18

Velocity

Answer 18

The velocity of an object is its speed in a given direction

Question 19

Newton’s
First Law

Answer 19

If the resultant force acting on an object is zero and the object is:

▪ stationary, the object remains stationary
▪ moving, the object continues to move at the same velocity

Question 20

Newton’s
Second Law

Answer 20

The acceleration of an object is proportional to the resultant force acting on the object and inversely proportional to the mass of the object

Question 21

Newton’s
Third Law

Answer 21

Whenever two objects interact, the forces they exert on each other are
equal and opposite

Question 22

Stopping
distance

Answer 22

The stopping distance of a vehicle is the sum of the distances the vehicle
travels during the driver’s reaction time (thinking distance) and the
distance it travels under the braking force (braking distance)

Question 23

Momentum

Answer 23

Momentum is defined as mass times velocity

Question 24

Conservation
of momentum

Answer 24

In a closed system, the total momentum before an event is equal to the
total momentum after the event

Question 25

Amplitude

Answer 25

The amplitude of a wave is defined as the maximum displacement of a point on a wave away from its undisturbed position

Question 26

Wavelength

Answer 26

The wavelength of a wave is the distance from a point on one wave to the equivalent position on the adjacent wave

Question 27

Frequency

Answer 27

The frequency of a wave is the number of waves passing a point each second