What do you already know about energy

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 3

What do you already know about energy

Today we will see what you still know or already know about this topic

In between the questions there will be some information

What is the range of this thermometer?

1. 0 degrees Celsius
2. -40 to 120 degrees celsius
3. -40 to 50 degrees celsius
4. 30 degrees fahrenheit

The scale on a thermometer (celsius) is based on...

1. temperature-scale of Kelvin
2. boiling point and melting point of water
3. boiling point and melting point of alcohol
4. not based on anything

Thermometer

Range - maximum to minimum 

(what temperatures can you measure)

Reading the middle part of the thermometer

22 kW =

1. 2,2 . 10^4 W
2. 2,2 . 10^3 W
3. 2,2 . 10^2 W
4. 2,2 . 10^1 W

17 MW =

1. 1,7 . 10^4 kW
2. 170 . 10^4 kW
3. 1700 . 10^4 kW
4. 17 . 10^4 kW

Powers of ten

k = 1 000 = 10^3

M = 1 000 000 = 10^6

G = 1 000 000 000 = 10^9

m = 1/1 000 = 10^-3

micro = 1/1 000 000 = 10^-6

nano = 1/1 000 000 000 = 10^-9

plastic

copper

iron

Feathers

Aluminium

Wood

Insulators

Conductors

Conductors

Electricity and heat can travel through easily

Mostly metals are used for this

Insulators

Heat and electricity will have a hard time moving throught the material

plastics

Thing with a lot of air in them

You are mixing a smoothie using a blender. at that moment the current throught the wire is 2.17 A. The blender is connected to a socket via a plug. What is the power of the blender?

Power

Formula for power is:

P = U x I

Hasans father has asked him to hover the living room. This takes him 15 min. The power rating of the vacuum cleaner is 600 W. Calculate how much energy (in kWh) the vacuum cleaner has consumed during that time

Formula for energy

Formula for energy is :

E = P x t

Joules = Watt (J/s) x sec

kWh = kilowatt x hours

Battery

wind

Uranium

Sun

Oil

Electrical energy

Food

Water

Coal

Chemical energy

Radiant energy

Nuclear energy

Kinetic energy

What kind of energy conversion takes place in a wind-turbine

1. Electrical to chemical
2. Chemical to nuclear
3. Kinetic to Electrical
4. Kinetic to chemical

Energy source

What is an energy source

Where does energy come from

Form of energy

What is the type of energy

Way the energy is transported or stored 

Energy conversion

Method to change one type of energy to another

Chemical energy in fossil fuels -> thermal energy -> electrical energy (powerplant)

What is the correct formula for
heat-loss

1. Q = U x A x dT
2. U = Q x A x dT
3. A = U x Q x dT
4. dT = U x A x Q

What is the unit for specific heat?

1. J/g°C
2. °C/Jg
3. g/J°C
4. J/°Cg

Heat 1,25∙10^3 g of water until the temperature has increased by 75 °C. The specific heat of water is 4.2 J/g∙°C.

Select the correct heat supplied.

1. 3,9⋅10​5​​J
2. 3,9⋅10​4​​J
3. 3,9⋅10​3​​J
4. 3,9⋅10​2​​J

Specific heat

The specific heat of a substance is the amount of energy required to increase the tempeture of 1 gram of any substance by 1 degree.

From water it is: 

The character is c (small letter)

This is a substance property.

4,2Jg⋅​0​​C

/

Heat 

Heat = specific heat x mass x temperature difference

If the specific heat is small, then...

1. warming and cooling takes a short amount of time
2. warming and cooling takes a large amount of time
3. heating takes long, cooling is quick
4. heating is quick, cooling takes long

Degrees

Jouls per gram per degree

Gram

Joules

C

J

g

J/g/C

Heat energy

Mass

specific heat

Temperature change

Q

m

c

ΔT

Which is NOT a type of heat transfer?

1. Radiation
2. Convection
3. Heat flow
4. Conduction

Heat transfer

The movement of heat energy from one warmer place to another colder place through conduction, convection or radiation

Heat transfer 

by convection

Heat can move around freely in a liquid. Therefore cooking is a great way to heat up your food. 

The liquid will make sure that all parts of the food come into contact with the heat, while at the same time it prevents the food from burning because it will not get too hot at any one point.

 

Heat transfer 

by conduction

Metals can conduct heat very well, that's why for cooking we mainly use metal pans. 

But some metals conduct better than others, therefore you see a lot of copper pans in a professional kitchen.

Keep in mind that if a material heats up very quickly, it will cool down quickly too.

Heat transfer 

by radiation

Heat radiation is one way for the heat to move around. Every object with a lot of heat in it, can emit this heat again as heat radiation. 

Matt black objects are very good at absorbing heat, but can also radiate a lot of heat as well.

Heat radiation is also called infrared radiation. This type of radiation cannot pass through glass and is reflected by shiny objects.

Heat radiation is one way for the heat to move around. Every object with a lot of heat can emit heat as heat radiation. Matt black objects are very good at absorbing heat, but can also radiate a lot of heat as well.

Heat radiation is also called infrared radiation. This type of radiation cannot pass through glass and is reflected by shiny objects.

Summary heat transfer

Conduction:

The flow of heat through physical contact,

Some materials conduct better than others

Convection:

Heat transfer due to motion of a fluid or gas.

If the temperature rises, the density drops making the fluid or gas go up

Radiation:

Heat transfer by electromagnetic waves.

When these electromagnetic waves are absorbed by an object the object gets warm.

Heat radiation waves need air to transfer heat

1. true
2. false

Heat transfer is caused by

1. Heat
2. Absorption
3. Change in temperatures
4. The oven

In which phase is conduction the only means of heat transfer, as convection cannot take place?

1. solid
2. liquid
3. gas

Good luck 

See you only once more before the testweek

recap chapter 3.1 to 3.3

Practice material in classroom and info in magister