Lesson video

Hi, everyone, my name is Miss Hummel, and today we'll be answering the question, how can we measure the size of forces? We will learn how to measure the size of forces, particularly how we can measure weight.

We will also learn about Isaac Newton and his contribution to our knowledge of forces, as well as Newtons as a unit of measurement.

And we will also investigate how to use a Newton metre to measure forces.

Our lesson will follow this structure.

First we will learn about Isaac Newton, then we will discuss the differences between mass and weight and what Newtons are, we will then discuss how to measure in Newtons by using Newton metres, and then we will end off with some application questions.

In this lesson, you will need an exercise book or paper, a pencil or pen, a coloured pencil or pen, and a ruler.

If you haven't got those things, pause the video now and go get them.

Star words are the most important words of the lesson.

When I go like this, it's going to be my turn to say the words.

And when I go like this it will be your turn to say it out loud.

Our star words today are, forces, mass, weight, Newton, Newton metre, gravity, and grammes.

We will start off by learning about Isaac Newton.

Now, he was a British scientist who lived between 1643 and 1727 in England.

He was a very well known scientist, and he made a very big impact in the scientific world, as well as Britain in general.

Can we work out how long he lived for? Bringing in a little bit of maths into science.

Now, if you did work it out and paused the video, it was 84 years which at the time would have been a very long time for someone to live.

One of the things that he studied in a lot of detail was forces, which is why we care in our unit of forces so much about who Isaac Newton was, and what he did.

Because we care so much about who he was and what he did, we're going to watch a video on Isaac Newton.

Now with that, Isaac Newton sure thinks very highly of himself.

Now, I would like us to focus on mass versus weight and Newtons.

We know how strong a force is by finding out how many nutrients of force or N are used.

Now, Isaac Newton's studies were so helpful that the measurement of forces was named after him.

There's not a coincidence that the measurement that we use for forces is called Newtons.

Now, to understand Newtons, we first need to understand the difference between mass and weight.

Mass is the amount of matter or stuff in an object.

Weight is the force of gravity acting on an object.

Mass is measured in grammes or kilogrammes.

Weight is measured in Newtons.

Now, this may seem confusing to some of you because in everyday life, you probably hear people referring to mass as weight all the time.

This used to really confuse me when I was a student because they're not the same thing.

I used to hear my mom saying, oh this way is grammes or kilos.

But what would have been scientifically correct was for her to say things like the mass of this is grammes or kilos.

So weight is measured in Newtons, not in grammes or kilogrammes.

And a lot of people use them interchangeably, that means they use one for the other, when actually they are very separate things, if we're thinking of it scientifically.

So you are going to have to think like scientists and remember something that is very difficult for many people to remember, which is that mass is what we're referring to when we're discussing how much someone weighs or how much some fruit weighs at the supermarket, what we mean is how much mass it has.

The weight of an object is measured using a Newton metre.

And it's a measure of how hard gravity is pulling on an object.

Now, we discussed the gravitational force and we said that it's a type of non-contact force.

For you to get an idea about how Newtons work, there is about one Newton of weight that is acting on an orange, but there's about 70,000 Newtons of weight acting on a large lorry.

We're going to watch a video that's hopefully going to clear up some of our questions about mass and weight.

I would now like you to pause the video to answer this question, what is the difference between mass and weight? And what are they each measured in? You can resume once you've finished answering that question.

Next in this lesson, we're going to look at Newton metres.

The size of a force is often measured using something called a Newton metre, which is a spring with a hook with a scale along its length, going up in Newtons.

The stronger the force is acting on the hook, the larger that the measurement will be.

Here's some pictures of Newton metres.

They're not very common and they're not usually used by people who are not scientists.

I have, however, got all of these with me here today.

Now, to measure the weight of an object, you hold the Newton metre upright, and place it on the hook.

For example, if I was measuring the weight of this very cute stuffed animal, I would hook it onto my Newton metre, making sure that it is nice and straight.

I would check the measurement on the Newtons.

Now, right now it's saying it's about two Newtons.

To measure a sideways force like friction, you hook the Newton metre onto the object and you pull from the left to the right.

Here's our next activity.

You will have to label the photo.

If you don't have the photo in front of you, sketch your own Newton metre that you can label.

It says, the at the top can be used to.

The numbers at the side that say N show.

The at bottom can be used to.

Now pause the video now to complete the task.

Here are our answers.

Please mark them with a different coloured pen or pencil.

The hook at the top can be used to hold the Newton metre.

The number at the side that says N shows us the weight or size of the force.

The hook at the bottom can be used to connect the object or force that you are measuring with the Newton metre.

For this final part of our lesson, we're going to think like scientists and interpret and present some data.

These Newton metres have been marked.

You should write down how much force has been measured on each of the Newton metres below.

Pause the video to complete this task.

Here are answers, mark them with a different coloured pen or pencil.

The Newton metre on the left was approximately showing four Newtons.

The one in the middle was approximately showing 15 Newtons.

And the one on the right was the hardest one which was showing approximately 2.

25 Newtons.

Now, I know it's about 2.

25 because it's halfway between two and 2.

5, and 2.

5 is the same as 2.

50.

I would now like you to pause the video to answer this question, how do we measure the weight of an object with the Newton metre? You can resume once you're finished answering the question.

Our final activity will be to record the results of me measuring some things in Newtons and grammes.

You will write the item, the weight to Newtons and the mass in grammes.

You'll be wondering throughout, if you can make any generalisations based on our data.

Now, generalisations refers to something that can be seen in our experiment, which we can apply to other situations.

Now, I've got a series of items. We'll stick to four items and I've got both Newton metres that I can use to measure Newtons, and I've also got a scale that I can use to measure in grammes.

So then you'll be able to write down the item I used, the Newtons and the grammes.

Let's use our beloved stuffed monkey to begin with our measuring.

Now, first, we're going to measure the Newtons by holding it like this.

Now, earlier I said it was two, but now that I can see it from the front, I think it is about 2.

5.

We need to write that down, 2.

5 Newtons.

I'm going to measure it with my scale, and it's 242 grammes, so I'm writing that down as well.

That was my first item.

Next I've got a kitchen utensil.

Now, I use this to stir in my spaghetti which I will be making later for dinner.

Now, I'm going to measure it first with the Newton metre.

Thankfully, it's got a little hook there for me.

Now, it's saying it is pretty much exactly 0.

5 Newtons.

So that's half a Newton.

Lets now weigh it with our scale.

It's saying it's 55 grammes.

Next we can use this bottle.

It seems to be about, let's say 4.

4 Newtons, and it is 448 grammes.

And finally, we've got my handy pencil case.

It seems to be 6.

1 Newtons, so that's the heaviest thing so far, and it is 620 grammes.

Great, so I'm going to repeat what all of them were.

So I had my stuffed animal which was 2.

5 Newtons and 242 grammes.

My kitchen utensil was 0.

5 Newtons, which was 55 grammes, my bottle was 4.

4 Newtons, which was 448 grammes.

And my pencil case was 6.

1 Newtons, which was approximately 620 grammes.

Now, I wonder if based on that data you can make any generalisations.

Now I noticed, for example, when I had six Newtons, it was 600 and something grammes.

When I had four Newtons, it was 400 and something grammes.

When I had 2.

5 Newtons, it was nearly 250 grammes.

So I think that a generalisation we can make is that one Newton is approximately 100 grammes, which means that 10 Newtons is approximately one kilogramme.

Make sure to write down that generalisation.

We have now finished our lesson, and it's time for you to complete your exit quiz.

You need to exit the video, and complete the quiz to test your knowledge and understanding of this lesson.

I hope you enjoyed the lesson as much as I did.

I now need to clear things up, bye.