Lesson 12 — Activity 1: How Simple Machines Work
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Lesson 12 — Activity 1:
How Simple Machines Work
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In
science, energy is the ability to do work, to cause change, or to make
things move. Knowing that definition, you can more easily see why the
study of energy includes a lesson on simple machines. Because simple
machines have one kind of movement, we can use these machines to help us
move an object more easily than we could by ourselves. In this lesson, you will look at how some simple machines can do work.
If energy is the ability to do work, what is work? You might think of work as studying for a test or going to a part-time job after school. In science, the definition of work is different:
Work is the result of a force (a push or pull) moving an object.
Work is the result of a force (a push or pull) moving an object.
For
example, you may know that mountain biking can feel like hard work! When
you are pedaling uphill, you are doing work because you are applying
force to the pedals, you are moving, and you are raising your body
(and the bike) up the hill. When you are coasting downhill, however, you
are not doing work. You are moving, but you are not applying any force.
Enjoy the temporary rest!
For example, you may know that mountain biking can feel like hard work! When you are pedaling uphill, you are doing work because you are applying force to the pedals, you are moving, and you are raising your body (and the bike) up the hill. When you are coasting downhill, however, you are not doing work. You are moving, but you are not applying any force. Enjoy the temporary rest!
Scientists use a measurement to determine how much work is done in
various situations. Because work involves a force moving an object, the
equation to calculate work done is this:
Work = Force × Distance
or
W = f × d
or
W = fd
Work = Force × Distance
or
W = f × d
orW = fd
Everyday examples of work include walking up stairs or lifting heavy objects. Whenever work is done, energy is transferred from one place to another. The measurement for force is a unit called newtons (N). Both energy and work are measured in joules (J) (which are newton metres).
Let's try an example!
If a man pushes a concrete block 10 metres with a force of 20 N, how much work has he done?
Answer:
Work = Force x Distance
Work = 20 N x 10 m
Work = 200 J
Work = Force x Distance
Work = 20 N x 10 m
Work = 200 J
Now, you try it!
What is the work involved in moving a shopping cart the distance of 10 metres with a force of 12 N?
Click on the box to the right to check your answer!
Answer:
Work = Force x Distance
Work = 12 N x 10 m
Work = 120 J
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