Lesson video

Hi everyone, my name is Miss Hummel and together we'll be answering the question, what are non-contact forces? In this lesson, we will recap the definition of non-contact forces.

We will also investigate gravity and gravitational force and learn about Galileo by completing an investigation.

Finally, we will learn about magnetic force, including some uses for magnets.

Our lesson will follow this structure.

First, we will recap what non-contact forces are.

Then we will dive into learning about gravity and gravitational force.

Finally, we will discuss and investigate magnetic force.

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.

Here are star words, which are the most important words of our lesson.

I'm going to say them and ask you to repeat them after me.

When I point at myself, it will be my turn and when I point at you, it will be your turn.

Forces, non-contact, air resistance, gravity, magnetic force, gravitational force, South and North.

So the last one was just North not and North.

Forces and non-contact will help us with our definition.

Gravitational force and magnetic force are examples of non-contact forces.

There are lots of types of forces that can act on an object.

Sometimes those act, even if two objects are not touching, which is the opposite of a contact force, that's what a non-contact force is.

Examples of non-contact forces include gravitational force and magnetic force.

What are the two forces? Gravitational force and magnetic force.

Each object in a non-contact force is creating an invisible force on the other object in a way that we can't see, but we can feel and measure.

Which of these images do you think is showing gravitational force? Point it on your screen.

And which one is using magnetic force? Point at that one on your screen.

We're now going to complete an activity which is going to help us recap contact and non-contact forces.

First, you will answer the question, what is a non-contact force? Then I would like you to write down the names of the forces that we have learned into this table.

If you don't have a table in front of you, you can draw one using your ruler.

Pause the video now to complete the task.

You may resume once you've finished.

In this next part of the lesson, we will focus on gravity and gravitational force.

I would now like you to pause the video, to answer these recap questions.

first, what is the difference between mass and weight? What are they each measured in? Which one was related to gravity and how? You can resume once you've finished answering the questions.

You should have said, 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 kilogrammes and grammes.

Weight is measured in Newtons.

Weight is related to gravity as it's the force of gravity acting on an object.

Here's a problem for you to think about.

These two balls are the same size.

One has a larger mass.

If they were dropped at the same time, which one do you think would fall faster? And why do you think that? Now I have an idea about what I would have thought if I was your age.

Now, Galileo Galilei had the same question.

In 1590 he decided to carry out an investigation to find the answer.

He climbed to the top of the Leaning Tower of Pisa with two balls of similar shape and size, but have different masses.

Now, you may have heard of the Leaning Tower of Pisa before, it's found in Italy.

He dropped both of the balls from the top of the tower at the same time.

Both balls hit the ground at the same time.

Galileo's experiment proved that all objects fall at the same rate no matter what their mass is.

But this can seem really hard to believe.

We will naturally believe that items with larger mass, will fall quicker.

Now, we have another problem for you to think about.

Would a feather and a hammer fall to the ground at the same time? Why or why not? Now the answer is that in reality, the hammer would fall quicker.

However, that's not because the mass of the hammer is greater, even though it is.

We will watch a video here of what happens when you drop a feather and a hammer on the moon.

Kim we copied at both over wind and a penetrometer drum in the ETB.

At Coy Jeff, I haven't put the solar wind in yet but I will shortly.

I want to watch this, get out of the way.

A good picture it is.

Beautiful picture it is.

On my left hand, I have a feather, in my right hand a hammer.

And I guess one of the reasons we got here today was because of a gentleman named Galileo a long time ago, who made a rather significant discovery about falling objects in gravity fields.

And we thought that it would be a better place to confirm his findings on the moon.

And so we thought, we'd try it here for you.

And the feather happens to be appropriately a Falcon feather for our Falcon, and I'll drop the two of them here and hopefully they'll hit the ground at the same time.

I dropped them.

Galileo was correct in his findings.

Can you think of why the two objects fell at the same time speed on the moon, but the feather fall so much more slowly on earth.

What's different about the moon and the earth that would cause this to happen? Well, air resistance pushes on different objects with a different force, which is what causes the feather to fall much slower than the hammer in earth.

Air resistance pushes the feather up with a bigger force than it pushes up a hammer.

We were to draw diagrams and we had to draw gravity kind of pulling it down and we had to draw air resistance, kind of keeping it up.

The air resistance arrow on the feather would be much greater than the air resistance arrow on the hammer.

Since there's no air in the moon, there is no air resistance to push on the feather.

So the two objects are able to fall at the same speed.

If you would like to complete an optional investigation, you will need two plastic water bottles and some water.

If you would like to go get those things, you can pause the video now and go get them.

Now, for the optional investigation, you will need to follow these instructions.

First, you will fill one bottle to the top with water and put the lid on.

Only fill about a third of the other bottle and put the lid on as well.

Then try to drop both bottles from the same height at the same time.

If they both land without falling on their side, they should land at the same time.

This is basically the same as the experiment that Galileo completed from the top of the Tower of Pisa Our final section for today is magnetic force.

Objects called magnets attract magnetic materials like iron and steel.

They have two ends called magnetic poles.

You may be wondering what are some uses of magnets and can maybe have a hint with what is behind me.

First, computers, televisions and microwaves all use magnets.

Magnets keep our refrigerator door shut.

That's really important.

Now, I wish my fridge magnet was a little bit stronger because once I did shut the door, but it didn't shut properly of the freezer and everything in my freezer got defrosted.

And I woke up to a puddle of water and all my food had gone off, it was a very sad time.

Next, magnets are placed in stomachs of cows to catch metals.

I thought that was really interesting.

And lastly, magnet slow down roller coasters.

I love roller coasters so much that I'm so happy magnets exist so that we can make them work.

Now, two magnets can either attract each other or push each other away.

Now, point to the diagram where you think the two magnets are attracting each other.

Now, can you point to the one that shows magnets pushing each other away? When two objects pull each other together, we say that they attract each other.

We've already used the word attract so you should know what it means.

But when two objects push each other away, we say that they repel each other.

Try and come up with an action for attract and for repel.

In my head, I know what I would be doing for an action for attract and an action for repel.

When I've got these two magnets here, you can see that they want to come together.

When the opposite poles are touching each other.

However, if I were to put the same poles together, it's really hard to get them to touch each other because I'm feeling an invisible barrier that is making my hands move as I get them closer together.

The same thing happens when I do it with the other opposite poles.

It's like they want to go everywhere, except for I can force them if I'm very strong, but as you can see, my hands begin to shake.

Now, you may be thinking, okay, but some of the magnetic things I see don't look like this.

They don't look like these magnets that have opposing poles, which we can see here.

Now, some things are made from magnetic material, which may look just like little, nearly dust particles.

Now, if I were to get the magnet and put it underneath, watch what happens to the magnet particles.

So they were all sticking and I can move them with my magnet.

It's going on, a fun little journey across my page, going this way, going this way, changing direction.

Now, as I take it off, they kind of fall back again.

And even if I do it with either pole of my magnet, the same thing occurs.

I could probably make a beautiful little pattern, but I'm not so sure I'm skilled enough with these magnets.

So a lot of magnetic things are made out of these particles as well.

So I would like you now to try and answer those questions.

What would it feel like when two of the same side of the magnet are brought together? We just went through that.

And what would it feel like if two different sides of the magnet were brought together? Now, paperclips, what would happen if paperclips were put next to a magnet? Let's have a look at the paperclip.

Got my paperclip here, it does want to kind of stick to this side.

Let's see the other side.

It's also stuck to that side as well.

Let's just test the other magnet just in case.

So it's definitely sticking to both sides of the magnet.

So paperclips were attracted to sides of the magnet is what you're going to be answering.

Now pause the video to complete the task.

You can resume once you're finished and we will go through the answers.

To go through the answers, if you put two of the same side of the magnet together, it would feel like they're pulling each other together.

And if you put two of the different sides of the magnet together, it would feel like they're pushing each other apart or refusing to be brought together.

And lastly, paperclips were attracted to both sides of the magnet.

I would now like you to pause the video, to answer this question, what are some of the uses of magnets? You can resume once you're finished answering that question.

We have now finished our lesson and it is 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, bye.