Lesson video

- Hi, I'm Ms. Horsmith, and I'll be your physics teacher today.

Let's get started.

Today's lesson is energy stores and transfers.

We're gonna learn about energy stores and how energy is transferred between them and then take a look at some real life examples.

This is part of the energy topic within science.

First, let's take a look at the keywords you'll need for this lesson.

Energy can be described as being in different stores.

Energy can be transferred between different energy stores.

Energy transfers can be described using energy pathways.

There are three learning cycles within this lesson.

Energy stores, energy transfers and identifying energy pathways.

We're gonna start by looking at different energy stores.

There are several stores of energy.

Now you might have been used to hearing the word store referring to something like a cupboard or when we put things away, but an energy store in physics is just description of where or which form energy is stored in.

Energy stores can be measured in joules and that unit is given the capital J.

This is a unit just like any other unit you might have seen before.

Like distance is measured in metres or time is measured in seconds, energy is measured in joules.

Using the pictures there on the screen can you determine the names of the six energy stores we are gonna take a look at today? Okay, let's see how many of those stores you could name.

Moving objects store energy in their kinetic energy store.

That means that any object that has any kind of movement has kinetic energy.

And the faster that object moves, the more kinetic energy it will have.

Objects that have a really large mass can also have a large kinetic energy, especially if they're moving quickly as well.

Stretched objects store elastic potential energy.

In the picture there, I've got a bow and arrow.

So when that bow is pulled back it's gonna be stretched and that's storing elastic potential energy in the bow.

You may be able to think of some other things that store elastic potential energy, such as a spring, like the suspension on your bike or in a car and a rubber band.

They all store elastic potential energy when they are stretched.

A hot object has more energy in its thermal energy store than when it is cold.

So the hotter an object is the more thermal energy it will store.

The energy in the nucleus of an atom is in the nuclear energy store.

And we confuse and split atoms to release this energy.

Food, batteries and fuels store energy in a chemical energy store.

So a battery is the sort of most obvious example of a chemical energy store cause we can physically think about the chemicals that are inside a battery, but food is a great example as well.

Food has chemical energy within it and we need food to survive.

It's the way that we get our energy.

And different fuels are the chemicals that, say, a car might need, such as petrol.

That stores chemical energy.

Finally, the amount of energy in a gravitational potential energy store of an object depends on the height of the object.

So objects that are really high off the ground or have a higher gravitational potential energy than if that same object was closer to the ground.

Objects that are really heavy and high off the ground will also have even more gravitational potential energy as well.

Let's check how much you understand about those six energy stores.

The amount of energy in the energy store of an object depends on the height of the object.

Excellent, it's the gravitational potential energy store.

The higher the object is the more gravitational potential energy it will have.

Stretched objects store energy in their.

Energy store.

Great, it's the elastic potential energy store.

Objects that are stretched store energy in their elastic potential energy store.

Well done.

Moving objects store energy in their.

Energy store.

That's right, it's kinetic.

Kinetic energy store refers to objects that are moving.

Excellent.

Now it's your turn to practise your knowledge of energy stores and their descriptions.

I want you to draw a line to match the name of the energy store with its description on the right hand site.

Have a go now, pause the video and then press play when you're ready to take a look at the answers.

Okay, let's have a look at the answers.

So the kinetic energy store is stored in moving objects.

Well done.

The chemical energy store is stored in foods, fuels or batteries.

The elastic potential energy store is stored in objects that are stretched.

Well done so far.

The thermal energy store is stored as heat.

Hotter objects have more thermal energy.

The nuclear energy store involves splitting or fusing atoms and is to do the nucleus of an atom.

And finally, the gravitational potential energy store is stored in objects off the ground.

Amazing job if you've got all those right.

You've only just learned about those six energy stores, so to match them to their description is fantastic.

Let's move on to the second learning cycle in this lesson.

Energy transfers.

Energy can be transferred in four ways between those different energy stores.

All six of those energy stores can have energy transferred among them.

Let's take a look at the four different transfers.

Energy can be transferred electrically through a flow of charge.

Energy can also be transferred mechanically and that's when a force is applied to move an object through a distance.

Energy can be transferred by radiation using waves, such as light.

And energy can be transferred by heating where energy passes from a hotter to a cooler area.

Let's have a look at some real life examples of those different energy transfers.

A crane is an example of a mechanical energy transfer.

That's because the crane has to apply a force to move the object through a distance.

So that's an ideal example of a mechanical transfer.

A circuit is an example of an electrical energy transfer.

Any appliance or object that contains a circuit will have to transfer energy electrically.

And there's a picture there of a circuit that you might have seen in electricity lessons.

Light is one of the most common examples of transferring energy by radiation, but we can also transfer energy with other electromagnetic waves as well.

If energy moves from a hot object to a cold object, such as a hob heating up a source pan, then this is an example of energy transfer by heating.

The hot object will transfer energy to the cool object.

Okay, let's check your knowledge of energy transfers.

Energy is transferred.

When a force moves an object through a distance.

Brilliant, it's mechanically.

And we saw the example of the crane.

Energy is transferred.

When a mobile phone is charging.

It's electrically.

Well done if you got that.

You must have worked out that a mobile phone charger has a circuit within it and in a circuit we can have electricity.

So there must been an energy transfer by electricity.

Well done.

Now it's your turn to practise your knowledge of energy transfers.

Have a go at the questions on the screen.

Pause the video now and press play when you're ready to hear the answers.

Okay, let's have a look at the answers.

Identify the energy transfer taking place in the following scenarios.

A person picking up an object.

This is an example of a mechanical energy transfer because the person has to apply a force to move the object through a distance.

A cup of tea warming up a person's hands.

This is an example of an energy transfer by heating because the warm or hot cup of tea is gonna transfer energy to the person's hands, which shall be cooler.

Well done.

A toaster using infrared waves to toast some bread is an example of energy transfer by radiation.

Amazing job if you've got those three answers correct.

The last question was to give an example of an electrical energy transfer.

Now here I've put the example example of an electrical circuit transferring energy from a battery to a motor.

But you might have put any appliance or object that contains a circuit.

As long as there's an electrical circuit there'll be an electrical energy transfer.

Amazing job if you've got all those answers correct.

We're now gonna move on to the final learning cycle, identifying energy pathways.

Energy pathways describe the stores that energy is transferred between and how it's transferred.

So we've looked at the six different energy stores and we've looked at four different ways energy can transfer between them.

A pathway is just us putting those stores and linking them with the transfers.

An example of an energy pathway is there on the screen.

We can use boxes to draw energy pathways alongside arrows.

We normally refer to the main or initial energy store on the left-hand side in a box.

In this example, the kinetic energy store was transferred energy mechanically to an elastic potential energy store.

The energy transfer is always put above the arrow between the two energy stores in the sport, archery, pulling back the bow will transfer energy from the kinetic energy store when the person's arm moves to pull that bow backwards into the elastic potential energy store of the bow as it's now stretched.

The energy is transferred mechanically because that person has had to put a force to be able to move that bow backwards.

So it's applied a force through a distance.

And we could draw the energy pathway of this scenario at the bottom of the screen.

The kinetic energy store was transferred mechanically to the elastic potential energy store.

Have a go at completing the energy diagram below.

The engine of a car transfers energy from the chemical energy store of the fuel to the kinetic energy store of the car as the car moves.

The energy is transfer mechanically as the engine applies forces to make the wheels of the car move.

How could we complete that first box? Okay, it was the chemical energy store.

The scenario told us that energy was transferred from the chemical energy store of the fuel.

So that has to be filled in in the first box.

Well done.

Let's have another go.

A battery powered torch transfers energy from the chemical energy store of the battery to the thermal energy store of the bulb as it gets hot.

The energy is transferred electrically through the wires that connect the battery to the bulb.

Brilliant, the transfer there was electrically.

The scenario referred to there being a circuit and wires within the torch.

So this energy transfer was electrical.

Well done.

Now is your turn to practise your new knowledge of energy pathways.

Have a go at the questions on the screen.

Pause the video and press play when you're ready to check your answers.

Okay, let's take a look at these answers.

Draw energy pathway diagrams for the following scenarios.

A long distance runner transferring energy from their muscles into movement.

The long distance runner will transfer energy from the chemical energy store mechanically into the kinetic energy store of their muscles.

Remember, I said that humans need to eat chemical energy in order to be able to transfer it to kinetic energy.

The transfer was mechanical because the person will have to apply a force to move their arms and legs through a distance.

When they're moving, they then have energy in their kinetic energy store.

Well done if you got that one right.

An apple falling from the top of a tree.

When the apple's in the tree, it's going to have a high gravitational potential energy store cause it's stored off the ground.

This is then transferred mechanically into the kinetic energy store of the apple actually falling to the ground.

Well done if you got that one, it was quite tricky.

A pair of wet socks drying on a radiator.

Now this question was challenging because the initial energy store and where it is transferred to are the same energy store just in different objects.

So at the beginning there's a large thermal energy store in the radiator.

This is then transferred by heating as it's transferring energy from the hotter radiator to the cooler socks, and then the energy is transferred into the thermal energy store in the socks themselves.

And that will make the socks dry.

Really great job if you got that one.

That one was a really challenging one there at the end.

So well done.

Let's take a look at the summary of this lesson.

Energy can be transferred between different energy stores.

There are many stores of energy, and today we took a look at kinetic energy which is stored in objects that are moving, elastic potential energy stored in objects that are stretched, thermal energy in objects that are hotter, nuclear energy involved in fusing or splitting atoms, chemical energy stored in fuels, foods, and batteries and gravitational potential energy, which is stored in objects that are off the ground.

There are four ways that energy can be transferred between stores.

Electrically in a circuit.

By heating, if the transfer goes from a hotter to a cooler area.

Mechanically, if a force is applied through a distance.

And by radiation using different waves, such as light.

An energy pathway describes the stores the energy is transferred between and how it's transferred.

An energy pathway can be represented with diagrams that look like the one below.

We start off with an energy store in a box, we add the transfer across the top of an arrow and then we name the energy store that energy was transferred to at the end.

Thanks so much for joining me in this energy stores and transfers lesson.

See you next time.