Definitions

Question 1

Vector

Answer 1

A quantity defined by 3 things (magnitude, unit,direction)

Question 2

Scalar

Answer 2

A quantity defined by 2 things (magnitude,unit)

Question 3

Mass

Answer 3

A measure of the amount of matter of an object

Question 4

Weight

Answer 4

A measurement of how hard gravity pulling on an object

Question 5

Density

Answer 5

Mass per unit volume

Question 6

Hooke’s law

Answer 6

The extension of a spring is directly proportional to the force up to the limit of proportionality

Question 7

Pressure

Answer 7

The force per unit area

Question 8

Conservation of energy

Answer 8

Energy cannot be created or destroyed but can be transferred from one form to another

Question 9

Power

Answer 9

The rate of doing work

Question 10

Efficiency

Answer 10

The measure of the effectiveness of a device transferring energy into a desired form

Question 11

Principle of moments

Answer 11

when a body is balanced, the total clockwise moment about a point equals the total anticlockwise moment about the same point.

Question 12

Centre of mass

Answer 12

The point through which the entire mass of the object appears

Question 13

Centre of gravity

Answer 13

The point through which the entire weight of an object appears

Question 14

Atomic mass no.

Answer 14

The no. of protons and neutrons in a atom

Question 15

Atomic no.

Answer 15

The no. of protons in a atom

Question 16

Ionisation

Answer 16

When an atom or molecule become charged by gaining or losing an electron to form an ion

Question 17

Isotope

Answer 17

Atoms of an element with the same atomic no. but different mass no.

Question 18

Half life

Answer 18

is the time taken for its activity to fall to half of the original activity.

Question 19

Background radiation

Answer 19

Radioactive materials occur naturally without any obvious source

Question 20

Newton’s 1st law

Answer 20

The forces on a system are balanced, the object has 2 possible states of motion
Stationary or moving at constant velocity
Fr=0

Question 21

Newton’s 2nd law

Answer 21

The acceleration of a body is directly proportional to the resultant force

Question 22

Nuclear Fission

Answer 22

The splitting up of a large heavy nucleus into lighter nuclei with the release of energy

Question 23

Nuclear Fusion

Answer 23

When light nuclei fuse to create heavier nuclei with the release of energy.