Physics

Question 1

What is a force and it unit of measurement?

Answer 1

A push or a pull and it is measured in newtons (N)

Question 2

If a force is exerted on an object, what five things can happen?

Answer 2

speed up slows down 
Rotation 
Direction can change 
Object can come to a stand still
Deformation

Question 3

What is the definition of paired forces?

Answer 3

When each object exerts a force of equal size on the other object in opposite direction.

Question 4

Name the 2 types of forces and give their definitions?

Answer 4

Contact force : an object that touches another object

Non-contact : works over a distance

Question 5

Define gravitational force

Answer 5

A non-contact force where objects attract each other without touching

Question 6

Identify the 3 differences between mass and weight.

Answer 6

Mass indicates the amount of matter of an object, where as weight is the attractive force that the planet exerts on an object
The mass of the objects remains constant, where as the weight of objects can change
Mass is measured in KGS and weight is measured newtons (N)

Question 7

Define magnetic forces

Answer 7

It’s a non-contact force whereby magnets attract objects that consist of iron, nickel or cobalt.

Question 8

Define electrostatic forces

Answer 8

It is a non-contact force whereby an object is charged either positively or negatively.

Question 9

What 3 things does an atom consist of and where are they found?

Answer 9

Protons (+) and nucleons in the nucleus and electrons (-) in the space around the nucleus.

Question 10

True or false: an object is positively charged if it gives electrons away

Answer 10

True: object has more protons than electrons

Question 11

True or false: an object is negatively charged if it donates electrons?

Answer 11

False

Question 12

Explain the formation of lightning

Answer 12

• The droplets in the clouds rub against each other and get charged
• A lot of negative charges accumulate in the bottom part of the cloud and the positive charges in the top half of the cloud
• this causes a difference in potential energy.
• during discharge, potential energy is converted into electrical energy that is again converted to intense light and heat energy

Question 13

Name 5 safety measure during lighting

Answer 13

• Avoid trees
• Take shelter inside a building or a vehicle
• Avoid outdoor activities
• Unplug all electronics
• Do not bath or shower

Question 14

What is current (I) measured in?

What is another name for volatage and what is it measured in?

Answer 14

Amperes

Potential difference and it is measured in volts

Question 15

What is resistance measured in? (R0

Answer 15

Ohms

Question 16

True or false:in a series circuit current remains the same and collage splits

Answer 16

True

Question 17

True or false: in a parallel circuit current stays the same and voltage stays the same

Answer 17

False, current does split

Question 18

Define a conductor

Answer 18

A substance that allows a substance to pass through. Eg copper

Question 19

What is the function of a resistor?

Answer 19

To resist the flow of current.

Question 20

Name the 4 factors that influence resistance.

Answer 20

1. Type of conductor
2. Length of conductor
3. The thicker the conductor the harder it is for current to flow
4. The temperature

Question 21

Why is a voltmeter always connected in parallel?

Answer 21

Because it has a high resistance

Question 22

True or false: an ammeter is always connected in series

Answer 22

True

Question 23

Define an electricity meter

Answer 23

Measures how much energy is used in the household.

Question 24

What is a fuse?

Answer 24

A small piece of metal that is located in sockets which melts when there is a power surge

Question 25

What is a circuit breaker?

Answer 25

A switch that trips when the current become to high

Question 26

Name two advantages and disadvantages between fuses and circuit breakers

Answer 26

Fuses - disadvantage is that you have to buy a new one Advantage is that it’s cheap Circuit breaker - disadvantage is that it’s expensive Advantages is that it can be switched on

Question 27

Define a lighting conductor and explain its purpose

Answer 27

A metal rod with a sharp end that is fixed to roofs and another end is parted to the ground. It conducts from lighting into the ground

Question 28

What are the 4 results after electrical energy theft?

Answer 28

Power interruptions The stability and quality of electricity is effected They are expensive to replace Eskom cant keep up with the increasing demand for electricity for a growing population

Question 29

How do the South African consumers become affected by electrical energy theft?

Answer 29

They pay for the stolen electricity | A safety risk for electricity

Question 30

Name the 3 things that eskom are responsible for

Answer 30

Generation of electricity from coal Transmission over long distances Distribution to consumers