# Simple Machines in Action

In this worksheet, students will relate their understanding of simple machines to their application in the world around them, looking at how they are used in different ways.

Key stage:  KS 2

Curriculum topic:   Forces

Curriculum subtopic:   Mechanisms: Levers, Pulleys and Gears

Difficulty level:

### QUESTION 1 of 10

Either from your work in science, or if you've checked out the EdPlace activity 'Simple Machines', you'll know that simple machines are not complex and that three common ones you'll find in everyday life are...

LEVERS

GEARS

PULLEYS

So, what's their job? Simply, to make life easier. A lever helps you to convert your small force into a large one (just like a super-power!). A pulley changes the direction of a force so you can lift heavy things more easily. Meanwhile, gears help you to turn a slow speed into a fast one.

In this activity we're going to look at how these simple machines are all around you and, hopefully, to help you to look out for them in your daily life.

Scissors are a good example of a lever in action.

Look at this pair of scissors and choose where the fulcrum is located: A, B or C.

A

B

C

A door is another example of a lever that you use many times every day. The door handle is almost always placed at the edge of the door.

What do you think is the main reason for this?

So it's easier to turn the handle

So it's easier to turn when you're carrying stuff

So it doesn't get in the way when you walk through

So you use less force to open the door

Where the door pivots (opens/closes) is the fulcrum of the door.

What is the name of the (usually) metal objects attached to the door and the wall which allow the door to pivot (turn)?

Look at this picture of a crane.

It's clearly a complex machine but many of its functions depend on the simple machines that are part of its design.

Tick all the simple machines you think you might find that are part of the crane's design.

Wedge

Lever

Pulley

Inclined plane/ramp

Gears

Here is a picture of someone using a pulley to lift a heavy load.

The advantage of the pulley is that it helps you to lift a heavy load by pulling down on the rope.

What is the name of the force they are lifting the load against? Write your answer in the box.

A bike, like the crane in Q4, is a great example of a complicated machine with lots of simple machines incorporated into its design.

Here is a picture of how the brakes on the bike are applied.

In order to apply the maximum force to the brakes, where is it best to place your fingers when you pull?

At the end of the brake lever

Near where the lever pivots

In the middle of the lever

Attached to the brake lever is a metal cable which runs around a grooved slot and down the bike frame to the brakes.

When you pull the brake lever, the cable is pulled and operates the brakes.

What sort of simple machine is the cable and slot acting as? Write your answer in the box.

Although modern bikes have many different-sized gears, on older bikes the gear wheel by the pedals was a single-size gear wheel. Attached to the rear wheel was a 3-speed gear set, with three different-sized gear wheels.

Which of the three gears on the back wheel do you think would allow the rider to go fastest, by converting the rotation of the gear wheel by the pedal, into the fast motion of the rear wheel?

Largest gear wheel

Middle gear wheel

Smallest gear wheel

You might not expect to find simple machines as part of your body's design, but they're there! Take your arm for example - here is a picture of a hand lifting a weight:

What type of simple machine do you think this is?

If you moved that weight (from Q9) closer to your elbow, how would you expect that to change how much effort you needed to make to lift the weight (ignore the fact that your hand is best at holding objects)?

It would increase the effort

It would decrease the effort

It wouldn't make any difference

• Question 1

Scissors are a good example of a lever in action.

Look at this pair of scissors and choose where the fulcrum is located: A, B or C.

B
EDDIE SAYS
Remember the fulcrum? That's where a lever pivots, so it has to be B - that's where the two halves of the scissors turn about the pivot point - or fulcrum.
• Question 2

A door is another example of a lever that you use many times every day. The door handle is almost always placed at the edge of the door.

What do you think is the main reason for this?

So you use less force to open the door
EDDIE SAYS
Levers are force-multipliers. By having the handle at the edge of the door, your small force is enough to open the door as the width of the door multiplies that force. Go and try it for yourself! If possible, find a door with a closer thingy at the top (there are usually loads at school) - push the door open at the edge, in the middle and near the hinges. Same door each time, but which was easiest? Why?
• Question 3

Where the door pivots (opens/closes) is the fulcrum of the door.

What is the name of the (usually) metal objects attached to the door and the wall which allow the door to pivot (turn)?

hinge
hinges
EDDIE SAYS
So, doors are levers! The fulcrum of the door is the hinge which are metal structures which turn/pivot and allow the door to open and close. Go and have a look! Find your nearest door and check out the hinges - look at how they operate as the fulcrum of the door.
• Question 4

Look at this picture of a crane.

It's clearly a complex machine but many of its functions depend on the simple machines that are part of its design.

Tick all the simple machines you think you might find that are part of the crane's design.

Lever
Pulley
Gears
EDDIE SAYS
So, the arm of a crane is a lever that enables it to lift the load and slide them along the arm. The pulleys are there to raise the load off the ground or lower it down. Gears are part of the mechanism that allows the base of the crane to rotate. Wedges are things like an axe head: thin at one edge and fat at the other; meanwhile, ramps allow things to be slid uphill, neither of these two simple machines are built into a crane's design.
• Question 5

Here is a picture of someone using a pulley to lift a heavy load.

The advantage of the pulley is that it helps you to lift a heavy load by pulling down on the rope.

What is the name of the force they are lifting the load against? Write your answer in the box.

gravity
EDDIE SAYS
That's the beauty of pulleys, you pull down (with gravity) and the load is lifted up (against gravity). In fact, as you'll learn, you can join pulleys together (side-by-side) and things get way easier then as they share the load you're lifting. Cool right?
• Question 6

A bike, like the crane in Q4, is a great example of a complicated machine with lots of simple machines incorporated into its design.

Here is a picture of how the brakes on the bike are applied.

In order to apply the maximum force to the brakes, where is it best to place your fingers when you pull?

At the end of the brake lever
EDDIE SAYS
Remember, levers are force-multipliers: that means that the further away from the pivot the force is applied, the greater the effect it has. If you pull towards the edge of the brake lever, you can apply more force to the brakes than if you pull close to the pivot point (it's called leverage).
• Question 7

Attached to the brake lever is a metal cable which runs around a grooved slot and down the bike frame to the brakes.

When you pull the brake lever, the cable is pulled and operates the brakes.

What sort of simple machine is the cable and slot acting as? Write your answer in the box.

pulley
pulleys
EDDIE SAYS
A cable running around a groove that you can pull is a pulley! Bike brakes need quite a bit of force to apply them properly, the lever on the brake helps you do this and the cable attached to it means that the force you apply is transferred to the brake mechanism attached to the wheel.
• Question 8

Although modern bikes have many different-sized gears, on older bikes the gear wheel by the pedals was a single-size gear wheel. Attached to the rear wheel was a 3-speed gear set, with three different-sized gear wheels.

Which of the three gears on the back wheel do you think would allow the rider to go fastest, by converting the rotation of the gear wheel by the pedal, into the fast motion of the rear wheel?

Smallest gear wheel
EDDIE SAYS
Funny things, gears- if a small gear wheel is attached to a large one, as the larger one rotates, it makes the small one rotate faster. That's because the teeth in the gear wheels line up and as there are more in the large wheel, for every complete revolution of the big wheel, the little one has to make more than one complete revolution. Some bikers are very into their gears!
• Question 9

You might not expect to find simple machines as part of your body's design, but they're there! Take your arm for example - here is a picture of a hand lifting a weight:

What type of simple machine do you think this is?

lever
levers
EDDIE SAYS
Your arm is one of the levers in your body! Your elbow is the fulcrum and your forearm pivots around that point. Your hand is at the end so, in fact, that's furthest from the fulcrum and so the point at which the objects you're lifting exert the most force on you.
• Question 10

If you moved that weight (from Q9) closer to your elbow, how would you expect that to change how much effort you needed to make to lift the weight (ignore the fact that your hand is best at holding objects)?

It would decrease the effort
EDDIE SAYS
In theory, the closer the weight is to the fulcrum (that's your elbow), the less turning force it exerts and so the easier it would be to lift. OK, so your hand is best at holding things and the flat of your forearm is probably not brilliant at carrying a plate of food safely, but in pure physics terms, it's the least amount of effort you'd have to make to lift it.
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