Lesson video

Hi there everybody.

My name is Mr. Booth.

Welcome to today's lesson.

It's brilliant that you could join me.

Today we are looking at the physical properties of materials.

It's important that we can use physical properties of materials to select materials for the products that we want to use.

It's also important that we can differentiate between what a physical property is, and a working property.

So we're gonna have a look at that.

This lesson is part of the materials testing unit.

Today's outcome, I want you to be able to identify physical properties of materials.

We have three keywords for you today.

The first is physical property.

The characteristics of a material, such as its appearance and features.

We then have material, what a product is made from, and finally function, what a product is meant to do.

So keep a lookout for those keywords as we run through the lesson.

We have two learning cycles today, but first we're gonna look at the physical properties of materials, and then we're gonna select materials based on physical properties for products.

Material properties describe how a material looks, feels, and behaves.

They're important because they help designers choose the right materials for a product.

If the wrong materials are used, then things can go wrong very quickly.

Products can break, parts can wear out too quickly, or it might not even work properly at all.

As you can see with this umbrella that has obviously been discarded because it's broken, the materials choice could have been considered, which might have made it last a little bit longer.

Like people have physical characteristics to describe their appearance, such as eye color, skin tone, or hair type, materials also have physical properties and characteristics, like color and texture.

It's what you can see or feel without changing what it is, and that's the big difference between physical properties and working properties.

So here we have Sam.

And Sam says, "I have short hair and a piercing through my right ear." We have Jacob.

"I have afro-textured hair." And finally Aisha.

She's telling us that she wears a hijab.

Physical properties are the characteristics of a material that can be observed without doing anything to it.

So you can actually see it or you can feel it.

They help us identify and classify materials.

For example, color.

Well, gold is a yellow color, whereas copper is a reddish brown.

We can also think about the weight of materials as well.

Steel is heavy, where foam is light.

Quick check for understanding.

Which of the following is a physical property of a material.

Is it A, gold is yellow? B, a plastic ruler snaps under pressure? C, copper melts at just over a thousand degrees C? Or D, rubber stretches when pulled? Pause the video now.

Have a go at this and come back to me when you've got your answer.

It is of course, "Gold is yellow." A.

Well done.

So let's have a look at the types of physical properties.

So the types include appearance, such as transparency, so we can see through it.

The luster, so the shine of the material.

We have texture.

And we also have the color.

We have density, how compact the material is.

Absorbency, how well it soaks up liquid, or maybe how well it doesn't soak up liquid.

And then finally, conductivity.

And we can split this into two types.

Electrical conductivity, how well it conducts electricity, how well it lets electricity to flow.

And also thermal conductivity, how well heat passes through it.

Quick check for understanding.

Which of the following is a physical property of metal? Is it A, it rusts over time? B, it reacts with acid? C, it is shiny and cold to touch? Or D, it can be made into wires? Pause the video now.

Have a go at this and come back to me when you've got your answer.

It is of course, it is shiny and it's cold to the touch.

That's a physical property, or those are physical properties.

Let's have a closer look at a fabric.

So here we have silk.

So let's have a look at the physical properties of silk.

Well, first of all, it's lightweight.

It feels light.

If you pick up a silk scarf, it is quite lightweight.

The appearance.

Well, it's smooth, it's shiny, and it has a natural sheen.

That's why people like it so much.

Absorbency.

It absorbs moisture well, as do lots of textiles.

And of course, its texture.

It's soft and smooth to the touch, which is one of the reasons why it's so expensive.

So we're now onto your first task.

The images show four different materials.

What I want you to do is list the physical properties for each material.

I would like you to think about appearance, density, conductivity, and absorbency.

You might need to do a little bit of research to be able to complete this.

The first material is steel.

Then we have pine, we have wool, and also polyethylene.

Pause the video now, have a go at this, and come back to me when you've completed the task.

So how did you get on? Well, your answers might look like this.

So if we look at steel.

Well, it's dense.

It's shiny silver when polished.

It's magnetic.

It conducts electricity well.

It also conducts heat well.

And it has a smooth texture.

We then had pine, a light brown, yellow color, relatively lightweight.

It can show knots in the wood, which actually is a nice feature of it.

It's absorbent.

Anyone who's left anything wooden out in the garden for too long will know that.

And it can have a rough or even a smooth texture.

We then have wool.

Lightweight, soft to touch, absorbent.

It will absorb water well.

It can have a coarse or a fine texture, depending on the weave.

And of course, it insulates well.

It keeps us warm.

And then we have polyethylene.

Well, it's lightweight, it's waterproof, it has a smooth texture.

And of course, it's transparent, so we can see the liquid inside this bottle.

We're now onto the second learning cycle.

Selecting materials based on physical properties.

Now, when choosing appropriate materials for products, it's important to consider its function and the product's environment that it will be operated in or that it will be used in, to ensure materials with appropriate physical properties are selected.

Such as a towel.

Now, a towel is of course used for drying things, including us, so it needs to be made from an absorbent material such as cotton.

We also have a window.

Well, windows are designed to let light through.

Light into a building, but also so we can see out of buildings.

So it needs to be made from a transparent material, such as glass.

Quick check for understanding.

What is a product's function? Is it A, what it is meant to do? B, its color? Or C, its cost? Pause the video now.

Have a go at this and come back to me when you've got your answer.

It is of course, A.

What it is meant to do.

Let's continue with looking at our different products.

So outdoor seating.

It needs to be weatherproof and robust enough to withstand years of being cleaned and used outside.

So a good example of a material for this would be HDPE.

And we have indoor seating.

Well, this needs to have a softer texture.

It doesn't need to be as robust as outdoor seating, and it's no need to be weatherproof, 'cause it's not outside.

So polyester might be a more suited material.

Quick check for understanding.

Why is it important to consider the function of a product when selecting the right materials? Is it A, the material needs to be suitable for what the product is meant to do? B, the material should look bright and colorful? C, the material should be the cheapest available? Or D, the material will make the product heavier? Pause the video now, come back to me when you've got your answer.

It is of course A, the material needs to be suitable for what the product is meant to do.

Well done.

Now a table can be used to select materials based on the function and properties needed for products.

So here we have our table, and our headings are the product, the function, the physical properties, and then also a possible material from the other three headings.

So first of all, we have a car windscreen.

Now the function of a car windscreen is to provide protection and visibility for the occupants of the vehicle.

So let's have a look at some physical properties that we can take from that.

Well, first of all, it needs to be transparent.

It needs to allow light to pass through for visibility.

It also needs to be smooth.

It needs to help with aerodynamics of the vehicle.

And it probably needs to be quite dense, and it's usually laminated, and this is for occupant protection, in case any debris hits the windshield.

And then finally, a possible material for this would of course be laminated glass.

That would be a suitable material for this.

We then have a T-shirt.

And what is the function of a T-shirt? Well it is, of course, that it needs to be comfortable to wear.

What are the physical properties we can take from that? Well, it's gotta be soft.

It's gotta be comfortable to wear.

It's also gotta be absorbent, soak up sweat and water from our bodies, which is what makes it nice to wear.

And a possible material for this.

Well, it could of course be cotton.

So we're now onto task B.

For the products below, I would like you to research the function and the physical properties needed and suggest a suitable material.

First of all, we have classroom chairs.

And there's a hint in what you need to consider in that image.

We have a frying pan, a very nice-looking jumper there, and of course, kitchen towel.

Once you've done that, I would like you to select your own product, and I want you to do one that you can see now.

Try and find a product with a single material in it, and what I want you to do again, is research the function and physical properties needed, and suggest a suitable material for your own product.

Pause the video now, have a go at this, and come back to me when you've got your answer.

So how did you get on? Let's have a look at some sample answers.

Well, first of all, I wanted you to research the function and physical properties needed for each of these products, and then suggest a suitable material.

So here is my research and my suggestions.

So first of all, we had the classroom chair.

Well what is a classroom chair's function? It's gotta be comfortable to sit on, mainly.

It's gotta be easily moved and stacked.

And it's gotta be easily cleaned.

So the physical property as well.

Low density, so it's easy to move and stack, smooth, comfortable to sit on, and also that means it could be wiped clean easily.

Possible material, well I think polypropylene would be a suitable material for this.

We then have the pan, the frying pan.

What is the function of the pan? Well, it's to cook food, be easily clean, but also to look nice in the kitchen.

So, physical properties.

It's got to be a good conductor of heat to cook the food evenly and quickly.

And of course, it's gotta be smooth and shiny to look good and also be cleaned easily.

So possible material for a pan would be steel or aluminum.

We then have a jumper, the very nice-looking jumper.

Well, what's its function? It needs to be comfortable to wear, keep the user nice and warm, and also look nice.

So what are the physical properties? Well, it's gotta have soft fibers, so it feels nice on the skin, so it's comfortable to wear, and it can be dyed multiple colors.

It's also gotta be a good thermal insulator to keep the user warm, and a great possible material for this would of course be wool.

We then have the kitchen towel.

What is the function of kitchen towel? Well, it's to absorb moisture, but also be lightweight.

So physical properties.

Good absorbency, to soak up water from hands or whatever else we're trying to clean up.

It's also gotta have low density, loose fibers, so it can be lightweight.

And the possible material for this, nice and simple, it could of course be paper.

Then I asked you to select your own product.

I had a look around my desk, and I saw I had some electrical wires.

So what are the function of my electrical wires? Well, it is of course to transfer electricity.

So the physical properties.

It's got to be a very good electrical conductor to allow electricity to flow efficiently, and a possible material for this is, of course, copper.

Now these wires, of course, have insulation around them.

I'm just talking about the material in the middle.

Well done with that task.

I'm sure that you found your own product as well.

So that brings us to the end of today's lesson.

Let's have a quick summary.

Materials have physical properties such as color and texture that can be observed without changing them.

Choosing the right material is important so the product works properly and will last a long time.

The function of a product decides what material properties are needed.

You've been brilliant today.

I hope you enjoyed the lesson, and I look forward to seeing you all next time.

Goodbye.