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9.1 Mechanical work
What is the difference Doing work in physics
between the work In daily life we understand ‘work’ as
done by Maiya Maneza any useful activity of an employee,
lifting the bar and engineer, scientist or student, for
textbooks nis edu kz
the work of an office instance. But in Physics the concept
of work has a specific meaning. It is
manager? What do
a definite physical quantity that can
you understand by the
be measured. We call it mechanical work. For example, when a train
word ‘work’?
moves due to force, mechanical work is being done. This is because a
force is making an object move over a certain distance. When you open
a door, you are applying a force and making it move. So you are doing
mechanical work too.
By contrast, when a student makes a mental effort to think about a
problem, when you hold a mug without moving it, when you try to push
a heavy wardrobe but it is too heavy to move or you are carrying your
school bag on your back, these are all examples of situations in which the
mechanical work done is zero.
In a physical situation where either a) no force is applied or b) the
displacement of the object is zero, there is no mechanical work done.
Even if you have to exert a force to hold your mug in the air, there is
no work being done ON the mug because the force you are applying
is NOT making it move. The force exerted by your muscles is simply
holding the mug in the air.
OVER TO YOU!
1. Think of 5 different real-life situations in which work is done, and
5 in which work is not done.
2. What do you think the parameters might be for calculating the
work done?
REMEMBER! If a body moves under the effect of force, then mechanical
work is done. The greater the force acting on an object, or the greater
the distance covered, the greater the mechanical work done. If the body
does not move then the work equals zero.
Mechanical work is calculated by the following equation:
Work = force ∙ distance covered
or
A = F ∙ s
where A is work done, F is force and s is distance covered.
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