Hi, everyone.

I'm Dr.

Pemberton, and I'm pleased to be with you today.

I'm really looking forward to our lesson, which is called Air Resistance Plan.

In this lesson, we'll learn about air resistance and we're going to plan an investigation to help us study and understand it.

The learning outcome for today is that you can plan an investigation into the effect of air resistance.

It's part of our big question, how do forces make things happen? I'm looking forward to this, so let's move on to our learning.

These are the key words that we'll be using in today's lesson.

Force, air resistance, friction, fair test investigation, and variables.

Are you already familiar with any of these words? This is our definition slide.

It shows the meaning of each of the key keywords, but we won't go through each one now.

I'll explain them during the lesson when we need them.

After the lesson, you might like to come back to this slide to check you've understood each one correctly.

Here's our lesson for the day.

There are three parts to it.

The first part is air resistance.

Then we'll learn how air resistance can be helpful.

And finally, we'll think about scientists planning investigations into air resistance.

We're going to start now with air resistance.

Air is all around us, but we can't see it.

Sky is mostly air.

So what is it? Air is a mixture of different gases that surrounds the earth.

In this nice picture, we can see swans flying through the air.

Air doesn't look like much, but it does have a mass and it does get in the way of moving objects.

When objects move, they have to push the air in front of them out of the way.

The air hits the surface of the object and creates a force.

That force is called air resistance.

Air resistance is a type of friction force which acts between the air and the surface of the object.

In this picture, we can see a really beautiful owl flying.

Air resistance acts on birds like this owl.

It acts in the opposite direction to the movement of the object through the air, so it acts in the opposite direction to the way the bird is flying.

Because of this, air resistance slows down moving objects.

Air resistance affects objects falling down through air like a red skydiver in this diagram.

Gravity acts on the weight of the object and pulls it down.

Air resistance acts in the opposite direction and slows the object down.

In the diagram, gravity is acting on the weight of the skydiver and pulling them towards earth.

At the same time, air resistance acts in the opposite direction and slows them down.

Air resistance can also affect objects moving horizontally through air, so not just things falling down through it.

A force moves the object along in one direction.

Air resistance acts in the opposite direction and slows the object down.

Here, we can see an aeroplane flying from left to right on our screen, and we can see the air resistance acts in the opposite direction from right to left, slowing down the plane.

Are you ready to see what we've learned so far? Let's check by trying a couple of questions.

This is a missing word question.

I'll read it out and say "blank" where the missing words should go.

Air blank slows down moving objects and is a type of blank force.

Of course, the answer is air resistance, slows down moving objects and is a type of friction force.

How did you get on with that? Let's try another one.

This one is a multiple choice question.

When an object is moving, which direction does air resistance act in? Is it (a) the same as the movement, (b) opposite to the movement, (c) in all directions, or (d) only upwards? That's right, it's B.

When an object is moving, air resistance acts in the direction opposite to the movement.

Now, it's time for your first task.

In this task, you're going to try some activities to experience air resistance.

In all of them, you'll need to run across the playground.

You are going to be the moving object on which air resistance will act.

For the first time you do it, just run across the playground as fast as you can.

I wonder if you'll feel the air on your face.

Next, try the same thing again, but this time, do it holding a large piece of card in front of you.

Then do it again, but this time, put your coat on, only don't do up your coat.

Hold out the corners to make yourself as wide as possible.

A bit like you're trying to make your coat into a cape, but make sure you still stand straight up.

Don't lean over.

See how that feels when you run.

Finally, you'll need to do the last one with a friend.

Hold a large piece of fabric stretched between two of you so you have a vertical wall of fabric between you.

Now, try to run across the playground together, keeping the fabric stretched.

When you've done this, discuss how the different activities changed your air resistance.

Which moving surface is changing the air resistance in which case? That means what's the air hitting to slow you down in each case? And where is the air pushing against that surface? On its front, on its back, perhaps underneath it? Pause the video now while you do this, then come back to rejoin me for the rest of the lesson.

How did you get on? You may have had some experiences and some ideas like this.

Let's look at running as fast as you can first.

The child here says, "I was able to run fastest when I wasn't holding anything.

The only air resistance was from the air pushing on the moving surface of the front of my body." What about running with a piece of cardboard? This child said, "When I was holding a large piece of card in front of me, it was harder to run because there was an extra air resistance from the air pushing on the moving surface on the front of the card as well as my body." Let's think about running with your coat open.

Here, a child found this.

"When I used my coat to make myself as wide as possible, it slowed me down, because the air resistance was increased by the air pushing on the moving surface of my coat." And finally, let's look at running with a large piece of fabric.

How did that affect your air resistance? "Running was hardest when we were holding a large piece of fabric between us.

The air had the whole of the moving surface of the front of the fabric to push against." It's really good to practise explaining our science in complete sentences like this.

Sometimes, it's definitely easier to answer a science question with one word, but if we have to form the whole sentences, it really makes us think about explaining the science carefully and accurately.

Now, we're ready to move on to the second part of our lesson.

We're going to find out how air resistance can be helpful.

There are many cases where air resistance can be helpful.

Parachutes rely on pushing against the canopy to slow the falling person down.

Here, we can see a parachute with a lovely orange and white canopy stretched out above the person.

The air slows down the moving parachute.

Athletes use parachutes to make it harder to run, so they get fitter.

They call this resistance training, and I think it looks like really hard work.

This example looks exciting.

Wingsuits allow people to glide through the air as they fall, and parachutes are used to slow down vehicles.

Fantastic.

I'd love to have gone on that wingsuit, would you? Unfortunately, air resistance is sometimes unhelpful.

If we want to run fast or cycle quickly, air resistance can slow us down.

Can you think of other situations where air resistance is unhelpful? To avoid unhelpful air resistance slowing things down, engineers design vehicles with shapes that minimise their air resistance and make it easier to push through air at high speeds.

Just like we can see with this high speed aeroplane, it's narrow and pointed at the front.

To minimise the air, it has to push out of its way.

Similarly, large trucks have something called fairings on the top.

I bet you've seen these, but you may not have known their name or what they're for.

Fairings are the curved tops on large trucks to help 'em push through the air when travelling long distances on motorways.

It's time to see what you can remember with a couple of questions.

This is a multiple choice question.

When you run, what does air resistance do? Do you think it (a) slows you down, (b) does not affect your speed, or (c) speeds you up? That's right.

It's A, when you run, air resistance slows you down.

Let's try another one.

This one is another multiple choice question.

How do parachute work? Is it (a) air pushes down on the top surface of the canopy, (b) air pushes up on the bottom surface of the canopy, or (c) air pushes the person up towards the canopy? That's right, it's B.

Parachutes work because air pushes up on the bottom of the surface of the canopy, and this slows down the rate of falling.

Now, it's time for you to do some more science.

This one is a thinking and discussing task.

Lucas, Sam and Izzy are talking about air resistance.

Lucas says, "Air resistance is never helpful." Izzy says, "Air resistance is always helpful." And Sam says, "Air resistance is sometimes helpful and sometimes unhelpful." Explain who you agree with and give examples to support your choice.

Pause the video now while you do this, then come and rejoin me to carry on with the rest of the lesson.

Welcome back.

Who did you agree with and why? Well, Sam is correct.

She was right when she said, "Air resistance is sometimes helpful and sometimes unhelpful." Air resistance is helpful when it slows down parachutists, when it allows athletes to do resistance training, and when people use wingsuits.

It's unhelpful when it slows down runners and cyclists who want to go as fast as possible.

Let's move on to our third and final section today.

We're going to look at how scientists plan investigations into air resistance.

Engineers and scientists are very interested in air resistance.

You can see an engineer working in this picture.

Air resistance is really important in the design of vehicles and structures that interact with the air.

Air resistance affects how easily objects move through the air.

Scientists can plan fair test investigations about air resistance.

They can answer questions with them about air resistance.

What sort of questions could you ask about air resistance? Jun wants to investigate parachutes and air resistance.

What could his question be? Well, Jun could ask, "Does the shape of the parachute canopy affect air resistance?" Or he could ask, "Does the area of the parachute canopy affect air resistance?" Ah, yes, the area is the size of the canopy.

Hmm, both of those are good questions, which could be answered scientifically.

Jun decides to carry out an investigation to answer this question.

Does the material of the parachute canopy affect air resistance? He plans to time how long it takes a parachute to fall a fixed distance.

What could the variables be in this investigation? The variables could be the material of the parachute canopy, the area of the parachute canopy, the shape of the parachute canopy, or the height the parachute is dropped from.

Can you think of anything else? Which variables should he control and which should he change? So June asks, "Does the material of the parachute canopy affect air resistance?" To answer his question, he must only change the material of the parachute.

Only changing one variable allows us to know that no other variable has affected the results of our tests.

Let's see what we can remember about in planning investigations with a few questions.

The first one is a missing word question.

I'll say blank where the missing word goes, and you decide what it should be.

Objects with greater air resistance will move more blank than objects with less air resistance.

That's right.

Objects with greater air resistance will move more slowly than objects with less air resistance.

Let's try another one.

This one is a multiple choice question.

Air resistance affects how easily objects move through (a) water, (b) air, (c) mud, or (d) sand.

That's right.

It's B, air.

Now, it is time for your final task.

For this task, you need to plan an investigation to answer this inquiry question: does the area of the parachute canopy affect air resistance? Okay, so June investigated how the material of the canopy affected air resistance, and we're thinking about the area of the canopy.

Before you start writing, it's important to discuss your ideas.

So discuss the following.

What will you do? Which variable will you change? Which variables will you control or keep the same? And what will you measure and how? Once you've discussed this, record your ideas with a list of numbered instructions for your method.

And also, make a list of the variables and identify the one you will change.

Pause the video now while you do this, then come and rejoin me to carry on with the lesson.

Welcome back.

So your task was to plan an investigation to answer the inquiry question, does the area of the parachute canopy affect air resistance? Your plan might have looked like this.

Cut out squares from plastic bags in three different sizes, 10 by 10 centimetres, 30 by 30 centimetres, and 60 by 60 centimetres.

Two, tie or stick string to each of the corners of the parachute.

Three, tie the other end of the four strings to a paperclip and attach a piece of sticky tack to it.

That must be to weight it.

Four, drop each parachute from an agreed height and measure how long it takes to hit the floor.

So measure the time it takes to hit the floor.

Was your plan like this or did you have other ideas? I wonder which variable you identified as the one you would change.

It should be the size of the parachute.

Well, we're nearly at the end of our lesson, so let's look at the summary to remind ourselves of what we have learned today.

Air resistance is a force caused by air moving against the surface of an object.

Air resistance acts in the opposite direction to the moving object.

Air resistance slows down moving objects.

And air resistance can be helpful and unhelpful in different real life situations.

Thank you for joining me for this science lesson.

I've really enjoyed learning about air resistance.

I'm pleased to know the science behind parachute now, and I think I'll explain it to someone at home this evening.

Maybe you could too.

Well done for your hard work and have a great day.

And I'll see you next time.