Gang

Question 1

Define Speed

Answer 1

Distance moved per unit time

Question 2

Define Velocity

Answer 2

Rate of change of displacement

Question 3

Define Acceleration

Answer 3

Rate of change of velocity

Question 4

Define Vector quantities

Answer 4

Physical quantities that have both Magnitude and direction

Question 5

State Newton’s three laws of motion

Answer 5

1. Every object will continue in its state of rest or uniform motion in a straight line unless a resultant force acts on it
2. When a resultant force acts on an object of constant mass, it will accelerate in the direction of the resultant force, where
   F = ma
3. When body A exerts a force on body B, body B will exert an equal and opposite force on Body A

Question 6

Define Friction

Answer 6

The contact force that opposes or tends to oppose motion between surfaces of contact

Question 7

Define Mass

Answer 7

The amount of matter in a body

Question 8

Define Weight

Answer 8

The magnitude of the gravitational force of a planet acting on an object

Question 9

Define Gravitational Field

Answer 9

A region in which a mass experiences a force due to gravitational attraction

Question 10

Define Gravitational Field Strength

Answer 10

The gravitational force acting per unit mass of an object

Question 11

Define Inertia

Answer 11

The reluctance of an object to change its state of rest or motion due to its mass

Question 12

Define the moment of a force

Answer 12

The product of the force and the perpendicular distance from the pivot to the line of action of the force

Question 13

State the Principle of Moments

Answer 13

When a body is in equilibrium, the sum of clockwise moments about the pivot is equal to the sum of anti-clockwise moments about the same pivot

Question 14

Define centre of gravity

Answer 14

The point of an object where its whole weight appears to act

Question 15

Define Energy

Answer 15

The capacity to do work

Question 16

State the Principle of Conservation of Energy

Answer 16

Energy cannot be created or destroyed but can be converted from one form to another. The total energy in an isolated system is constant.

Question 17

Define Work Done

Answer 17

The product of the force and distance travelled by the object in the direction of the force exerted

Question 18

Define Power

Answer 18

The rate of work done OR the rate of energy conversion

Question 19

Define Pressure

Answer 19

The force acting per unit area

Question 20

Define Thermal Energy

Answer 20

Energy flowing from a region of higher temperature to a region of lower temperature. Net flow of thermal energy occurs only when there is a difference in temperature.

Question 21

Define Conduction

Answer 21

The transfer of thermal energy through a medium without any flow of the medium

Question 22

Define Convection

Answer 22

The transfer of thermal energy by means of convection currents in a fluid or gas due to a difference in density

Question 23

Define Radiation

Answer 23

The transfer of thermal energy in the form of electromagnetic waves such as infrared radiation without the aid of a medium.

Question 24

Define Specific Heat capacity

Answer 24

The amount of thermal energy needed to raise the temperature of a unit mass of a substance by 1°C

Question 25

Define Specific Latent Heat of Fusion

Answer 25

The amount of thermal energy required to change a unit mass of a substance from solid state to liquid state, without a change in temperature

Question 26

Define Specific Latent Heat if Vaporisation

Answer 26

The amount of thermal energy required to change a unit mass of the substance from liquid state to gaseous state, without a change in temperature

Question 27

Define critical angle

Answer 27

The angle of incidence in an optically denser medium for which the angle of refraction in the optically less dense medium is 90°

Question 28

Define Total Internal Reflection

Answer 28

The complete reflection of a light ray inside an optically denser medium at its boundary with an optically less dense medium

Question 29

Define Focal length

Answer 29

The distance between the optical centre and the focal point

Question 30

State the 3 general wave properties

Answer 30

1. The source of a wave is a vibration or an oscillation 2. Waves transfer energy from one point to another 3. Waves transfer energy without transferring the medium

Question 31

Define Transverse Waves

Answer 31

Waves that travel perpendicular to the direction of the vibration

Question 32

Define Longitudinal Waves

Answer 32

Waves that travel parallel to the direction of vibration (through a series of compressions and rarefactions)

Question 33

Define Amplitude of a wave

Answer 33

The maximum displacement of a point from the rest position

Question 34

Define Wavelength

Answer 34

The shortest distance between any 2 points in phase

Question 35

Define Period

Answer 35

The time taken to produce one complete wave

Question 36

Define Frequency

Answer 36

The number of complete waves produced per unit second

Question 37

Define wave speed

Answer 37

The distance travelled by a wave per second

Question 38

Define wavefront

Answer 38

An imaginary line on a wave that joins all adjacent points that are in phase

Question 39

Define sound

Answer 39

A form of energy that is transferred from one point to another as a longitudinal wave

Question 40

Define Ultrasound and state a use of it

Answer 40

Sound with frequencies above the upper limit of the human range of audibility (20Hz - 20kHz) Used in prenatal scanning to obtain images of structures in the body

Question 41

Define pitch

Answer 41

Related to the frequency of sound, the higher the frequency, the higher the pitch

Question 42

Define loudness

Answer 42

Related to the amplitude of the sound wave, the large the amplitude, the louder the sound

Question 43

State 3 properties of electromagnetic waves

Answer 43

1. They are transverse waves 2. Do not need need a medium to travel in 3. Travel at the same speed of (3 x 10^8)m s^-1 in vacuum

Question 44

Name the whole electromagnetic spectrum in increasing order of frequency and state a use of each type of electromagnetic wave

Answer 44

``` Radio waves: Radio Microwaves: Satellite television Infrared Radiation: Ear thermometers Visible light: Optical fibres Ultraviolet Radiation: Sunbeds/Sterilisation X-ray: Radiography Gamma rays: Radiation therapy ```