Lesson video

Hello, and welcome to this lesson on energy.

My name's Mr. Norris.

Now energy is such an important idea across all three science subjects, biology, chemistry, and physics.

And the idea of energy comes up time and time again in so many different topics.

So it's really important to begin to get a bit of an idea about energy, the scientific idea of energy, and when objects have energy, and what that means because it applies to everything in the Universe.

Let's get going.

The outcome of this lesson will be that you'll be able to identify different energy stores that objects have, and also explain why objects have each different store of energy.

Here are some keywords we're gonna be focusing on in today's lesson.

Chemical store, thermal store, kinetic store, gravitational store, and elastic store.

All of those are stores of energy.

Each of those ideas will be explained properly at the appropriate part in the lesson when they come up.

This lesson has just two sections.

The first section is about how all objects have energy in the different ways the objects can have energy.

And the second section of the lesson then introduces this idea of objects having energy stores.

So let's get started with the first section.

What are the different ways and reasons why objects, different objects have energy? So things can have energy for different reasons.

This football has energy because it's moving, and the higher the speed, the more energy we can say it's got.

And a moving object with a greater mass would also have more energy.

So let's do a very quick first check of that.

Which bowling ball do you think has most energy due to its movement? Is it bowling ball, A, is 8 kilogrammes going 3 metres per second? Bowling ball B, 8 kilogrammes going at 10 metres per second? Bowling ball C, 16 kilogrammes, that's double the mass with a speed of 3 metres per second.

Or bowling ball D, that's 16 kilogrammes with a speed of 10 metres per second? So which one do you think will have most energy due to its movement based on what we just said? Five seconds to decide.

Let's see if you chose the correct answer, which is option D.

Bowling ball D would have most energy due to its movement, even though it's going the same speed as bowling ball B, both of those are 10 metres per second compared to A and C, which is slower.

D would have more energy 'cause it's got more mass, as well as being at the faster speed.

Here's a second way that objects can have energy.

This apple has got some energy because it's raised up on that pile of books.

So the higher an object is raised, the more energy it has in that higher position, and the mass of the object and the strength of gravity also affect the energy.

Here's another way that objects can have energy if they're stretched, this rubber band has energy in that photograph because in that photograph is being stretched, but it's not just being stretched, objects can have energy because they're stretched and they want to spring back, but also if they were squashed, and they want to spring back up to their full shape, they would also have energy if they're squashed.

And the greater the distance an object is stretched or the greater of the distance an object is squashed, then the more energy it will have.

And how hard it is to stretch or squash an object, also affects the energy that object stores when it gets stretched or squashed a certain amount.

Here's another way that objects can have energy, objects have energy if they contain chemicals that can react.

Now there's five key examples of this, which it's important to try and remember.

So different things that have energy because they contain chemicals that can react, the first thing is food.

Food gives you energy when you eat it because food contains chemicals that can react.

And when the chemicals react within your body, that is what enables everything your body does to happen.

It's all enabled by the energy transferred from food that you eat.

Fuels also have energy because they contain chemicals that can react, and the chemical reaction that happens to fuels is they get burnt, burning is a chemical reaction.

So I'm thinking of fuels like the gas that's burned in a gas boiler at home, or the gas that's burned in a Bunsen burner, or the petrol that's burned in a car engine, or even the wax of a candle that's a fuel too, because it contains chemicals that can react by being burnt.

Batteries contain chemicals that can react.

When a battery is used and provides electricity to a circuit, what's actually happening within the battery is a chemical reaction.

So batteries are a store of energy because they contain chemicals that can react, that's really important.

The human body is also a store of energy because it contains chemicals that can react, and most of the chemicals in your body come from and they're built out of the food that you've eaten.

The same is true of plants and plant material.

Plant material contains chemicals that can react.

Some plant material can be burnt like wood from trees.

Other plant material contains chemicals that can react because that plant material becomes food like potatoes or apples that get eaten, for example, even leaves and grass contain chemicals that can react, they're a store of energy, and other animals make use of that by eating leaves and grass.

And then, of course, we humans make use of that by eating some of those animals, sometimes.

So to recap, five key examples of objects that have energy if they contain chemicals that can react, food, fuels, batteries, the human body, and plants, food, fuels, batteries, the human body, and plants, try saying that a few times over in your heads to try and make it stick.

Food, fuels, batteries, the human body, and plants.

And, of course, in all of those cases, the type of chemicals and the amount of chemicals is gonna affect the amount of energy.

So I did say to try and say those five things out loud a few times to make them stick in your heads.

So let's see if you can remember them.

Can you give the five examples of things that have energy because they contain chemicals that can react.

Five things that have energy because they contain chemicals that can react, the five things we just said, what did they start with? Have a go at saying them out loud now, and then we'll check.

Hmm, how many of the five were you able to remember? If you struggle to remember all five, this little clue might help.

So have another go now at saying all five examples of things that have energy because they contain chemicals that can react, out loud now.

Okay, hopefully, the picture prompted you to say out loud, food, fuels, batteries, the human body, and plants.

Well done if you did get all five.

Here's a final way we're gonna talk about today, that objects can have energy, it's because of their temperature.

So this cup of tea has energy because of its temperature.

Cups of tea are usually quite hot, but actually, it's not just things which are hot that have energy because of their temperature, things which are colder, have energy because of their temperature as well.

It's just obviously because they're colder, they're gonna have slightly less energy for every gramme of material that they're made from.

So the higher the temperature, the more energy for each gramme of material that the object's made from.

And, of course, the mass and the material that something's made from is also gonna affect the energy stored when something's at a certain temperature.

So if you had two objects at the same temperature, then the one with the bigger mass could well store more energy, of course, depending on the material that it's made from too.

So let's recap.

When an object has energy, the object could be moving, be raised up, be stretched, or squashed.

It could have a temperature, any temperature, hot or cold, or the object could contain chemicals that can react.

All of those properties would mean an object has energy.

So what's missing from this list? Five seconds to see if you could fill in the blanks, off you go.

Okay, let's see how you got on.

When an object has energy, the object could be moving, could be raised up.

Remember lifting something higher has more energy when it's higher up, something could be stretched or squashed.

Something could have a temperature, any temperature, cold or hot, it means something, stores at least some energy 'cause of its temperature, and the higher the temperature, the more energy stored, and the final one, objects can contain chemicals that can react, that means an object has energy.

Well done if you've got most of those.

So having energy means having properties that allow objects to interact with each other, so objects can cause changes and make things happen.

It's important to emphasise that it's the properties of the object and the objects themselves that make things happen, not the energy, okay? For example, that bowling ball can affect the pins because it's moving, and because it's moving, we can say it's got energy.

This mug could fall, it could speed up as it falls, and cause changes below because it's high up, and because it's high up, we could say it's got energy, and this hot water bottle can raise the temperature of cooler objects around it so it can affect its surroundings because of its properties, because it's hot.

And also because it's hot, we say it's got energy.

So energy, in a way is kind of shorthand for saying an object is able to interact with its surroundings, cause changes, and make things happen.

But remember, it's not really the energy that makes things happen, it's the properties that the objects have.

So let's do a little check on your understanding of energy so far.

Which of these best describes energy based on what we just said? Is it, A, energy is a force that makes things happen? B, energy is a substance that makes things happen? Or C, having energy allows objects to make things happen? Which best describes energy? Choose now, A, B, or C, five seconds.

Well done if you chose option C, energy is not a force, a force is a push or a pull, that's not what energy is.

Energy is not a substance, substances are solid liquid, or gas, and energy, that's not energy, energy is something different.

Energy is something we say objects have when it has certain properties that allows objects to make things happen.

So having energy allows objects to make things happen.

Well done if you've got that one.

Let's do another check now, I would like you to match each object in the pictures to the most obvious reason that it has energy.

So we've got a giraffe toy on a shelf, a toy car, going along that track, we've got petrol, filling up a real car.

We've got a kettle full of water, it looks like, and we've got that spring in that picture.

So which is the most obvious reason, each one has energy? One of them has energy 'cause it's moving.

One of them has energy 'cause it's raised up.

One of them has energy 'cause it's stretched.

One has energy 'cause it contains chemicals that can react, and one has energy because of its temperature, most obviously.

So have a go at matching those up, five seconds, off you go, Right, we'll go through the answers now.

Hopefully, that was fairly straightforward.

So the toy on the shelf has energy because it's raised up.

That toy car has energy 'cause it's moving, it's a bit of a blur in the picture on that track 'cause it's moving.

The petrol has energy because it contains chemicals that can react, it's a fuel, that's one of the five things that contain chemicals that can react, Food, fuels, batteries, the human body, plants.

The kettle contains energy because of its high temperature, quite obviously.

And the spring has energy because it's stretched.

So hopefully, that was fairly straightforward, and you got 5 out 5 on that.

Very well done if you did.

So we're now ready to do the task for this part of the lesson.

We've got five objects here, and for each object, I'd like you to state whether each object has energy or whether it has no energy.

For each object that has energy, I want you to explain the reason why, or reasons why it has energy.

So have a go at that now, and you need to use your pen to write an answer for 1, 2, 3, 4, or five.

Firstly, does each one have energy? And secondly, if it does have energy, then explain the reason or reasons why, off you go.

Pause the video now, and have a go at that task, Right, well done for your effort in that task, I'm gonna go through some feedback now.

So a person taking a nap has energy.

A common mistake is to think, "Well, oh, they're sleeping, they've not got any energy." But that's the everyday meaning of the word energy, not the scientific meaning of energy that we've been talking about all lesson so far.

So they do have energy and the reason is because the human body contains chemicals that can react, and also body temperature, everything has energy because of its temperature.

You might have also thought about, "Well, actually, there'll be some slight movements of the lips if they're making that ZZZ sound if they're asleep, or snoring, or the rise and fall of their chest as they're breathing, or even their heart beating." So I suppose at the moment when their body, those parts of their body actually are moving, technically you could say that those parts of their body do have some kinetic energy at those moments, but it's not one that is often useful to focus on.

The second object was a packet of crisps, that's food, so that has energy because crisps contain chemicals that can react, and also they have a temperature, everything with the temperature has a store of energy.

Number 3, the rock balanced at the top of the cliff.

This is another one that students sometimes forget that it has energy because it's high up.

Anything that's raised high up has energy.

And, of course, it's got a temperature, like all objects.

Number 4, a person resting after a long run.

Well, they have energy for the same reason that the person napping has energy 'cause the human body contains chemicals that can react, and also because of their body temperature.

People sometimes say, "Oh, I'm so tired, I've got no energy." But that's not the scientific meaning of the word energy, they're describing their feeling rather than the scientific idea of energy.

And then number 5, a ball rolling along.

I think most people normally get this one right, it does have energy because, of course, it's moving, and, of course, it's got a temperature.

So well done if you've got that all of those objects do have energy, it's actually very, very difficult to identify objects that don't have energy.

In fact, really, all objects have energy in one way or another.

So well done if you've got answers along the right lines for all of those five.

Now we've looked at some different ways that objects can have energy, let's give those ways some names.

And the names that we give to the different ways that objects can have energy are energy stores, so let's look at those now.

So we say that objects can have energy in different energy stores.

So, for example, food.

Food has energy because it contains chemicals that can react.

So what we say, food has a chemical store of energy, and that just means it has energy 'cause it contains chemicals that can react.

But food also has energy because of its temperature 'cause food is hot, often.

And we can, therefore say, that food also has a thermal store of energy.

So that's the name we give when objects have energy because of their temperature, we say that the object has a thermal store of energy, as well as the chemical store of energy, that it has because it contains chemicals that can react.

So food has more than one store of energy because of its different properties, that means it stores energy in at least these two different ways.

If that plate of food was up on a tabletop as well, then maybe you could say the plate of food also has a gravitational store of energy because it's raised up, and so on.

So all of the different properties that an object have, can mean that it stores energy in different ways or it has different energy stores.

So let's look at some more examples of that.

Here's an aeroplane.

We can say this aeroplane has energy because it's moving, so the word we give for that is that we say, that the aeroplane has a kinetic store of energy.

The word kinetic comes from Greek, kineos, which means movement.

So it's a good word for energy because of movement.

But the aeroplane also has energy because it's high up.

We say it has a gravitational store of energy, and the word gravitational is chosen because it's really the energy something has when it's in a certain position or a certain height upwards in a gravitational field.

So something has to be high up in a gravitational field to have energy because it's high up.

That's why things that are high up, we say that they have a gravitational store of energy, that's the name we give to that idea.

This spring also has energy.

It has energy 'cause it's stretched.

So that's a different reason, and the word we give for that is we say that the spring has an elastic store of energy, and we call it an elastic store of energy, whether something is stretched or whether something is squashed.

And that's because the word elastic isn't actually the name for a material, even though people can describe the elastic in like a waistband of trousers, the word elastic really means being able to spring back to its original shape, from being stretched or from being squashed.

So elasticness is all about returning to its original shape.

So when something is pulled out of its original shape by being stretched or squashed down from its original shape, by being squashed, and if the object has the property of being able to spring back, that's called being elastic.

So that's why the word elastic is chosen, okay? Things which want to spring back to their original shape after being stretched or after being squashed, they have an elastic store of energy.

So we say that different objects can have different stores of energy because of their different properties.

Let's do a little check on what we've just gone through.

Please match each property on the left to the correct name of the correct store of energy that objects can have when objects have that property.

Have a go at doing that now.

Five seconds to try and do the correct matchings, off you go.

I'm gonna go through the answers now, so pause the video if you've not finished yet.

Okay, and if something's moving, we say that's a kinetic store of energy.

It might be worth saying that out loud a few times, so you get the feeling for the word when something's moving, it's a kinetic store of energy.

When something has a temperature, that's a thermal store of energy.

Therm is always associated with temperature, like thermometer is what we use to measure temperature.

So when something has a temperature, we set a thermal store of energy.

If something's raised up, that's the gravitational store of energy.

If something's stretched or squashed, that's an elastic store of energy.

And if something contains chemicals that can react, then we're gonna call it a chemical store of energy.

Well done if you've got all five.

Here's one way that might be helpful for remembering the names of these five energy stores, these five ways that objects can have energy.

I call it GTECK, okay, G-T-E-C-K.

The G stands for gravitational stores of energy when things are high up.

T stands for thermal stores of energy.

E stands for elastic stores of energy.

C stands for chemical stores of energy, and K stands for kinetic stores of energy, GTECK, GTECK, GTECK, gravitational, thermal, elastic, chemical, kinetic.

It might be worth at this point, pausing the video and just saying that out loud to yourself a few times.

It might sound a bit silly, but saying something out loud can really help it to stick more in your memory for longer.

So GTECK, gravitational.

thermal, elastic, chemical, kinetic.

GTECK, GTECK, GTECK, the names of the five energy stores that we've looked at.

Right, so can you remember them? If you've been making notes, turn 'em over, don't look at them.

Can you recall the names of the five energy stores we've just been talking about? What was the way of remembering them? Can you say them out loud? Okay, off you go.

Try and do that now, firstly, with no clues at all, off you go, and try and remember all five.

Hmm, how do you think you got on? If you need a bit of help, try again using this.

And if you need a bit more help remembering all five, here are some pictures.

Right, I'm sure you'll have got almost all five if not all of them now, so I'll just run through them.

The five energy stores, GTECK, gravitational, thermal, elastic, chemical, and kinetic stores of energy.

Well done, for remembering all five.

Let's do another check of your knowledge of these energy stores.

This time I'd like you to match each object, each picture in the top row, to the most obvious energy store it has in the boxes.

Off you go, and have a go at doing that, five seconds.

I'm gonna go through the answers now, so pause the video if you need to, if you need a bit more time.

So I'll go through the objects one by one.

The hot water bottle is a thermal store of energy.

That's because of it's, most obviously, it's a thermal store of energy because it's hot.

The battery is a chemical store of energy.

Remember, batteries was one of the five key examples of things which are chemical stores of energy, things that have energy because they contain chemicals that can react.

Can you remember all five? Food, fuels, batteries, the human body, plants.

The toy on the shelf is a gravitational store of energy 'cause it's high up.

The rubber band is an elastic store of energy 'cause it's stretched in that picture, and that spitting toy is a kinetic store of energy 'cause of its movement.

So hopefully, that was fairly straightforward, and well done if you got all five.

Let's do another check that we can identify what energy stores an object has.

But in this case, the object is a person, and in this case, the object has more than one store of energy 'cause of its different properties that it has.

So have a go at filling in the gaps to identify which stores of energy the climber has.

Five seconds, off you go.

Okay, pause the video if you need a little bit more time.

I'm gonna go through the answers now.

So the climber has, in the first gap, which store of energy 'cause they're high up? That's gravitational, well done if you've got that.

A gravitational store of energy because they're high up.

The climber has which store of energy because their body contains chemicals that can react? That's a chemical store of energy, I mean the clues in the description there.

And the final bullet point, the climber has which store of energy because of their body temperature? That is a thermal store of energy.

Okay, it's now time for you to put all that work on energy, all together in this task.

So for picture number 1 and for picture number 2, I would like you to identify the stores of energy in each picture.

And then for each one, briefly explain why the object has each energy store that you think it's got.

So picture number 1 is a picture of a moving steam train.

So you should start your answer by saying, "The steam train has.

." and then say which stores of energy the steam train has, and give the reasons why it has those stores of energy.

For picture number 2, the child is on a "bouncer" ride and the photograph is taken at a moment when they're being pulled upwards, as the whole body is moving upwards at that point.

And you should start your answer by saying, "The child and ropes together have.

." and then say which stores of energy the child and ropes together have, and why the child and ropes together have each store of energy.

So you need a pen.

You could write this in bullet points.

Use a bullet point for each store of energy that you think each object has.

Remember to use the sentence starters.

So off you go at that task now.

Now well done, for your effort on that task, you should have paused the video and finished that task, and now I can give you some feedback.

So for picture number 1, the steam train has.

Now it doesn't matter what order you do these in, I went for a thermal store of energy first because of the high temperatures of the water, the steam, and the high temperatures of the parts of the train.

The steam train also has a chemical store of energy because of its fuel.

And the fuel for a steam train is usually coal.

In fact, I think you can see coal in the picture there, just behind the engine, a pile of coal in the kind of big carriage behind the engine.

And coal is a chemical store of energy because it's a fuel.

And fuels are chemical stores of energy because they are chemicals or they contain chemicals that can react, in this case, the chemical reaction is burning, the coal gets burned, and that's what powers the steam train.

The steam train also has a kinetic store of energy because it's moving.

I don't think it's an elastic store of energy 'cause I can't see anything that is stretched.

And I don't think it is a gravitational store of energy because it's not really significantly raised above ground level.

Although, I suppose perhaps the track is a little bit raised above ground level, so I suppose you could have that one if you like.

Okay, number 2, the child and ropes together have.

And again, you can have these in any order, a gravitational store of energy.

'cause they're raised up off the ground, a thermal store of energy because of their temperatures.

an elastic store of energy because the ropes are stretched, a chemical store of energy because the child's body contains chemicals that can react from the food that the child's eaten.

And finally, the child and ropes together have a kinetic store of energy because they are moving as shown in the description of the picture.

So very well done if you've got lots of those.

Well done, that's the end of this lesson, which is an introduction to energy.

Here's a quick summary.

When an object has a store of energy, this means the object can make things happen because of its properties.

So here are the properties that objects can have that give them energy.

Objects that are raised up, have a gravitational store of energy.

Objects have a thermal store of energy 'cause of the temperature.

Objects that are stretched or squashed, have an elastic store of energy.

Objects that contain chemicals that can react have a chemical store of energy, and objects that are moving have a kinetic store of energy.