Topic 1 - physics

Question 1

Scalar

Answer 1

A physical quantity that has magnitude but no direction. Example: speed, volume and mass.

Question 2

Vector

Answer 2

A physical quantity that has both magnitude and direction. Example: displacement, velocity and acceleration.

Question 3

Resolving vectors

Answer 3

When 2 or more vectors are causing an effect, they can be resolved into a resultant vector. The resultant vectors magnitude and direction shows the overall effect caused by all the components.

Question 4

Density

Answer 4

Density is a measure of an objects mass per volume.

Question 5

Finding volume

Answer 5

Volume can be found using a ruler and geometry
example: volume of a cuboid is AxBxC

Finding volume through an irregular object can be done by measuring the amount of water it displaces.

Question 6

Newtons Laws

Answer 6

1st law: An object in motion will stay in motion and an object in rest will stay in rest unless acted on by an outside force.

2nd law: F=ma (explained more in topic 1 formula’s)

3rd law: Every action has an equal and opposite reaction.

Question 7

Mass

Answer 7

Refers to the amount of matter that makes up an object. (kg)

Question 8

Weight

Answer 8

The force on an object due to gravitational field. (N)

Question 9

Hooke’s law

Answer 9

Hooke’s law states that the amount of force applied to an elastic object is proportional to how far it stretches. However, if the object is overstretched it will not spring back. Hooke’s Law only applies if an elastic object is not overstretched.
(not my definition)

Question 10

Circular motion

Answer 10

When an object moves in a circle it’s constantly changing direction, as velocity is a vector, a change in direction means a change in velocity. Due to the acceleration formula, this change in velocity means the object is accelerating and therefore must be experiencing a force.

Question 11

Moments

Answer 11

Moments refers to a turning effect on an object about a pivot point.

A spanner can be used to maximise the turning effect needed to loosen a bolt.

Question 12

Centre of mass/gravity

Answer 12

Point where gravity or weight appears to act through.

For regular shapes the centre of mass is the geometric centre of the object.

For irregular shapes, the object mass must be hung of different points and a vertical line drawn directly down.

Question 13

Momentum

Answer 13

Momentum is always conserved.
In order to change momentum a force must be involved.

Question 14

Collisions

Answer 14

Elastic collisions: kinetic energy and therefore momentum is fully conserved.

Inelastic collisions: kinetic energy and therefore momentum is not conserved due to energy losses in other forms. For example heat and sound.

If momentum is conserved, it means the total momentum before the collision is equal to the total momentum after the collision.

Question 15

Impulse

Answer 15

Impulse describes a change in the momentum of an object. It also describes the forces involved during the change in momentum.

Question 16

Energy

Answer 16

Energy is the ability to do work.

Energy stores:
Kinetic
Gravitational potential
Elastic potential (strain)
Nuclear
Electrostatic
Thermal (internal kinetic)

Energy transfers:
Mechanical (forces)
Electrical
Heating
Electromagnetic, sound or other waves

eg) GpE —> kE + thermal

Thermal produced sound waves.

Question 17

Kinetic energy

Answer 17

The energy of moving objects

Question 18

Conservation of energy

Answer 18

Energy cannot be created or destroyed. It can only be transformed from one store to another.

Question 19

Gravitational potential

Answer 19

Energy stored when an object is raised to a height within a gravitational field.

Question 20

Work

Answer 20

The term ‘work’ is used to describe a transfer of energy.

If an objects energy changes we say “work has been done:”

Question 21

Power

Answer 21

Defined as the rate at which work is done, or the rate of energy transfer.

Power is measured in watts (w). This is equivalent to Joules per second (J/s)

Question 22

Boiler

Answer 22

Uses heat from the burning of fuels to boil water into steam.

Question 23

Turbine

Answer 23

Transforms thermal energy from a fluid (liquid or gas) into rotational kinetic energy.

Question 24

Generator

Answer 24

Consists of coil (or coils) of wire that rotate in a magnetic field to produce an electrical current.

Question 25

Sources of electricity production

Answer 25

Hydroelectric
wind
tidal/waves
solar
fossil fuels
nuclear
geothermal
bio fuels

Question 26

Energy efficiency

Answer 26

No energy transfer is 100% efficient. There is always some energy lost.

Question 27

Pressure

Answer 27

Pressure is a measure of force per area.

The SI unit for pressure is the pascal (Pa) which is essential N/m².

SI - system international.

Question 28

Pressure in liquids

Answer 28

Liquid pressure is the increase in pressure at increasing depths in a liquid.