Upthrust is also known as...

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If the upthrust is less than the weight of the object, the object will

If the upthrust is equal to the weight of the object, the object will...

Which factors affect an object's ability to float?

﻿Hi, everyone. My name is Miss Hummel, and together we will be answering the question: What impact do gears, levers, and pulleys have on forces? In this lesson, we will first aim to understand the purpose of simple machines. We will then focus on gears, levers, and forces to find out how they work and how they can be useful. We will also complete some questions throughout the lesson which will help us check our understanding. Our lesson will follow this structure. First, we will discuss what simple machines are. Then we will individually discuss levers, followed by pulleys, and eventually gears. In this lesson, you will need an exercise book or paper, a pencil or a pen, a coloured pencil or pen, and a ruler. If you haven't got those things, pause the video now to go get them. Here are our 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. Levers. Gears. Pulleys. Fulcrum. Simple machines. And those are the words that we need to remember throughout the lesson. We will begin by discussing what simple machines are. A simple machine is an object that helps us turn a large force into a small force. Sometimes it can be difficult to create a force that is big enough to do the job that you would like to do. For example, to lift up an extremely heavy object or raise a large object up to a tall height. I had this issue when I moved houses, and I had to get a sofa up three flights of stairs. Now, in order to do these things, we can use simple machines to make the job easier. A simple machine is an object that helps us turn a large force into a small force. Now, let's think of a way to act out that definition. I'm going to say a simple machine. It's simple, it's just like, so imagine it's a square, it's not a square, is we can say is an object that helps us turn a large force into a small force. So a simple machine is an object that helps us turn a large force into a small force. I would now like you to pause the video to answer these questions. What is a simple machine, and what are the three types of simple machines that we need to know? You can resume once you're finished answering the questions. Next, we're going to discuss what levers are. Now, a lever consists of a pivot or a fulcrum, they're the same thing in this case, an effort, and a load. Levers are helpful when we want to raise a large object or a load off the ground. And lever is made from a long, thin object placed over a pivot or fulcrum. Remember, we can use either word. A pivot or fulcrum is a small object that the lever is placed on to enable the lever to turn. So in our diagram, we can see the load, which is whatever we're trying to lift with that lever, the pivot or fulcrum in the middle, below the long, thin object used for the lever. And then we can see the effort where we would need to manually put some effort in to get the lever to work, so that's like the strength of our muscles. Now, this diagram reminds me of something that you might see at a playground. What do you think it is? And you may have been thinking of a seesaw. Seesaw used to be one of my favourite things to play with with my younger brother. I always wondered how it could be so easy to lift up the person with the seesaw, but so hard if I tried to lift him up myself. You're now going to pause the video to label the diagram with the parts of the lever. Pause the video to complete the task, and you can resume once you're finished. We're now going to mark our work. Now, you should have written load for the object that we're trying to lift, pivot for the object that's underneath the thin, long object that we're using as a lever, and effort is what we're going to use to move it. Levers can be arranged in different ways. We saw one already. The one we saw was load, fulcrum, and effort. Objects that use a load, fulcrum, and effort arrangement include a seesaw, a crow bar, which we could use to open boxes, and some scissors. There's also a fulcrum, load, effort arrangement which includes wheelbarrows and nutcrackers. Finally, we can also have the arrangement of fulcrum, effort, and load. Objects that use these arrangements include tweezers, kitchen tongs, and a spade. You may have been wondering how it works if the fulcrum is not always in the same spot. So we've got three examples here so that we can have a look. We can see how the load, effort, and fulcrum are distributed in these different objects. For the first one, we have the load, followed by the fulcrum and the effort. Now that's what we were seeing in our earlier diagram, so we're most familiar with that scenario. For the wheelbarrow, however, we can see that the fulcrum is actually on the wheel or almost at the front of our object. The load is in the middle, so what we're trying to lift is in the middle, and the effort we're still putting at the end like we were with the first one. Finally, we have a spade, which is a different arrangement altogether. We have the load at the front, in this case, where we're digging up maybe some soil. We have the effort in the middle which is where we're going to place some of our hands while holding the shovel or spade. And then we've got the fulcrum at the end, which is where the handle is. I would now like you to pause the video to answer this question: What are three examples of things that we use as levers? You can resume once you're finished answering the question. In this next part of our lesson, we're going to discuss pulleys. Pulleys are a kind of wheel with a ridge that a rope or string can be threaded through. If we connect our end of the rope or string onto a heavy object, and the rope was kind of hanging on something, we can pull down on the rope to easily lift the heavy object up to a great height, like we can see in our picture. All a single pulley does is it changes the direction of force, which makes pulling down easier than lifting up. That's because pulling something down is easier on our muscles than lifting something up. Now, can you think of an example where you may have seen a single pulley system? You may have been thinking about construction places, and therefore cranes, which uses single pulley system. Perhaps you were thinking about opening/shutting some blinds, which you might have to keep the light out. That uses single pulley system. Or you may have been thinking people had to get water out of wells, and they used to use a system like that as well. Using two pulleys together means that you need half of the force to lift it. Earlier, with one pulley, we still needed all of our force, but we were changing the direction of the force that we needed. However, when we use two pulleys, what it does is you need half of the force to lift it, and this gives us what we call a mechanical advantage. Have a go at saying that. Mechanical advantage. Can you think of an example where you may have seen a pulley system with more than one pulley? I would like you to pause the video to answer this question. What are three examples of things that use pulleys? Now, we only gave examples of things that use single pulley so make sure to think about those items that use single pulleys. You can resume once you're finished answering the question. In the next part of our lesson, we're going to look at gears. Gears are when two or more wheels with spokes or teeth connect together to help a small force turn into a big force. Now, when we say teeth, we don't mean our actual teeth. We mean that, in the gears, you can see those little bumps sticking out of it, and they do look a little bit like teeth. An example of where you might've seen gears is in bicycles. The gears used between the pedal and the wheels means that a small force can be used on the pedals to create a large force, which makes the bicycle move. We're going to watch a video that's going to tell us a little bit more about bicycles and gears. We've got some images of things that use gears. We already saw how bicycles can use gears. However, clocks have gears as well. By using those gears with a specified rotation rate, that means how often they rotate, and teeth, you can design the hand of a clock so that it moves once per second, once per hour, or once per day, if that's what you choose. And finally, you may have heard an adult discussing how they should change gears if they're driving a car. Now, cars also have gears. You may even have seen a gearstick before, which has numbers on it, like you can see in the image next to our car. I would now like you to pause the video to answer this question: What are three examples of things that use gears? You can resume once you're finished answering the question. I am now going to ask you to complete an activity. You will label the diagrams below to show which object is a lever, which object is a pulley, and which is a gear. Pause the video to complete the task. You may resume it once you have finished. We're now going to mark our work so make sure you've got your different coloured pen and pencil ready. Now, the motorcycle was using our gears. The man trying to lift a large concrete block was using a lever. And the woman trying to lift herself up was using a pulley system. 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 this lesson. Bye!

Which of these is NOT an example of a simple machine?

Which of these items uses a lever?

Which of these items uses a pulley system?

Which of these items uses gears?

What impact do gears, levers and pulleys have on forces?

Describe what gears, levers and pulleys are

Explain why gears, levers and pulleys are helpful, and give some examples

In this lesson, we will first aim to understand the purpose of simple machines. We will then focus on gears, levers and pulleys to find out how they work and how they can be useful. We will also complete some questions throughout the lesson which will help us check our understanding.

Science

Y5 Science

Key Stage 2

Year 5

Miss

Forces

UNIT

What are forces?

How can we measure the size of forces?

What are contact forces?

What are non-contact forces?

Which of these is NOT an example of a non-contact force?

What would it feel like if two different sides of a magnet are brought together?

Contact forces will only take place if...

Friction causes...

What do we use to measure mass?

What do we use to measure weight?

Lesson overview:What impact do gears, levers and pulleys have on forces?

Core Content

Forces: