Minds On
Making work easier
In the science of machinery, “work” refers specifically to the amount of effort required to move an object. This applies to putting any kind of object into motion – from pushing someone on a swing, to pulling open window blinds.
To make work easier, and require less effort to accomplish, what is something that people often rely on?
Press ‘Hint’ to access a possible answer.
Machines are devices that are used to make work easier because they reduce the amount of force required to accomplish a task.
Consider each of the following imaginary scenarios of completing specific tasks. For each scenario, you will be given two options for how to accomplish the task, and will be asked to select the option that would take less time and effort to complete the task.
Scenario 1: Washing a load of dirty laundry
For each option, select the corresponding level or work.
Scenario 2: Travelling a very far distance
For each option, select the corresponding level or work.
Scenario 3: Travelling to the top floor of a building
For each option, select the corresponding level or work.
After exploring the activity, can you identify what all three of the more efficient options have in common?
Press ‘Answer’ to access an explanation of what these objects have in common.
The more efficient, less work/effort options of a washing machine, a car and an elevator are all different types of machines!
Action
Innovation in Canada
This learning activity features emerging technologies, STEM contributions, and Canadian innovations that are making a difference.
Machines, mechanisms, and forces
Machines reduce the amount of effort needed to accomplish “work” or a specific task. All machines are made up of at least one simple machine, and systems with more than one, are considered complex machines. Simple machines are the most basic examples of devices that apply force to an object in order to make it move.
Let’s review some vocabulary by trying to match key terms to their explanations.
For each term, select the corresponding definition.
Examine the following animation to see some examples of simple machines in action.
Mechanisms and mechanical advantage
How exactly, in scientific terms, do machines really make work easier? The goal of a machine is to reduce the amount of effort it takes to apply the force required to move an object, in order to accomplish a specific task. However, there are many parts and systems within machines, and more than one type of force involved in these parts.
The amount of effort that someone needs to apply to a machine for it to cause motion is called the input force. We call it this because it is the amount of work being “put in”.
The amount of force that the machine “put outs” as a result of that input effort – for example, how far it pushes or pulls an object – is known as the output force.
Explore this animation of someone using an axe to accomplish the task of chopping wood. An axe is an example of the simple machine we call a wedge. The force they put in to swing the axe against the wood is the input, and the splitting of the wood represents the output.
At the centre of any machine, simple or complex, are the mechanisms that allow it to work: mechanisms are single-part moving parts that incorporate simple machines to change the type or direction of movement.
Mechanical advantage refers to how much a machine increases the effort or input force that is put in. For example, if you have to apply less effort or “input” to work the machine, that machine has a greater mechanical advantage!
Let’s review some more vocabulary by trying to match key terms to their explanations to make sure we understand them.
For each term, select the corresponding definition.
Ways that machines change forces
In order for machines to do the job of making tasks easier for people, they must change the force that a person applies in some way.
To learn more about the specific ways that machines can change the force that is applied to them, we will engage with the Research and Record steps of the Scientific Research Process.
Check out this video to learn about the steps of the Scientific Research Process.
There are three specific ways that machines can change the effort/input force:
- increase the amount of force that has been applied
- increase the distance over which the force is applied
- change the direction of the force
Explore the following images and descriptions to learn more about the ways that machines can change forces.
Forces in pliers
Some machines, like pliers, are specially designed to put out a stronger force than the force put in by the person using it. When plier handles are squeezed together, the jaws of the pliers can close around an object with greater force and strength than it takes to squeeze the handles.
Increasing distance with a rake
Certain tasks require a person to cover territory as well as produce a strong output, so another important function of machines is how they can increase the distance over which a force is applied. In the case of a rake, a person holds one end and moves their hands a small distance, and the other end of the rake will cover more territory, but with not as much force.
Flagpole directions
A final way that machines can change forces is when they reverse the direction of the force being applied by the person. Raising an object above their height can be a difficult task for a person, so machines that assist with moving objects by lifting them can offer a significant benefit. In the example of a flagpole (which functions as a pulley), a person pulls down on one end of the rope to raise the flag upward to the top of the pole.
A carousel of 3 images.
Image 1: Diagram of pliers with a thin arrow pointing to the handles labelled “Input force”. A thick arrow points to the jaws of the pliers labelled “Output force”.
Image 2: A person raking the leaves. The input force is the person's arms moving and the output force is the rake moving. The input distance is the person moving their arms a short distance and the output distance is the rake moving a longer distance.
Image 3: A person raising a flag using a pulley. Pulling the rope down is the input force and the rope pulling the flag up is the output force.
Brainstorm
Brainstorm
Consider the following question and record your thinking using a method of your choice, such as in print, digitally, or using an audio recording. Try to use some of the key vocabulary that has been reviewed throughout this learning activity.
- Which of the three examples appears to benefit the user most? How?
Press ’Key Vocabulary’ to review a list of the vocabulary terms that we’ve reviewed so far in this learning activity.
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Machines and the environment
Complex machines can have remarkable mechanical advantage! Often, the more sophisticated the machine design, the more work the machine is able to accomplish with less effort from the person operating.
While machines can greatly benefit humans, that does not mean, however, that they are beneficial in every way. Because of the electrical energy that is required to run certain machines, especially complex machines that run on electricity, machines that are used widely every day can cause major environmental harm.
Consider the three examples of machines from the Minds On section: a washing machine, a car, and an elevator. While each of these devices help make work easier for people, they also have damaging effects on the environment.
Press the following tabs to explore how each example of complex machines can negatively impact the environment.
- Use over 19 billion cubic metres of water every day.
- Emit massive amounts of CO2 greenhouse gas (16 million tons!).
- Can deposit microfibers from synthetic clothing into the water system.
- A well known source of pollution, there are nearly 18 million passenger vehicles in Canada, meaning their joint contribution to air pollution is massive.
- For every litre of gas used while driving, a vehicle produces 2.3kg of carbon dioxide.
- Car emissions also include other harmful greenhouse gases like, nitrogen oxide and carbon monoxide.
- While elevators help make buildings accessible to people, they also consume electrical energy to run even when they are not in active use.
- A three-story office building uses 3,800 kilowatt-hours per year, roughly the same as the average North American home uses in four months.
- The mechanisms in most elevators require a type of oil treatment to run smoothly, which can become hazardous if that oil contaminates the water system.
Did you know there are efforts being made to reduce the harm caused by these specific machines? Examine the following list for a sample of how some organizations are trying to make improvements:
- More sustainable washing machine designs are being produced by electronic appliance companies. In recent years, students at Nottingham Trent University in England began developing an adjustment to the design of a standard washing machine so that it would reduce carbon emissions, save fuel, and even further reduce the effort required by the person operating.
- Otis Elevator Company, one of the most well-established global elevator manufacturers, has been leading research and development into how to increase the energy efficiency and environmental sustainability of their elevators. They have developed a new technology for the elevator belt (which functions like a pulley) that makes their design 75% more efficient than other systems.
Brainstorm
Think about it!
You have explored facts about the ways that machines that help humans can also harm the environment. Consider the following question:
- Which machines can you think of that might be helpful to people, but also have a negative impact on the environment?
Record your thinking on paper, digitally, as an audio recording, or using another method of your choice.
Consolidation
Analysing advantages and disadvantages
Machines are an important part of daily life and are specifically designed to make work easier. You have learned, however, that machines do not only provide advantages to humans –machines can also have effects on the environment.
Recall the machines that we have focused on today:
- washing/drying machines
- cars
- elevators
Consider the advantages and disadvantages of each type of machine, and record your thinking using the following organizer or using another method of your choice.
Complete the Advantages and Disadvantages of Certain Machines organizer in your notebook or using the following fillable and printable document. If you would like, you can use speech-to-text or audio recording tools to record your thoughts.
Press the Activity button to access Advantages and Disadvantages of Certain Machines.
Activity (Open PDF in a new tab)Reflection
As you read through these descriptions, which sentence best describes how you are feeling about your understanding of this learning activity? Press the button that is beside this sentence.
I feel…
Now, record your ideas using a voice recorder, speech-to-text, or writing tool.