Work
 When a force causes an object to
MOVE in the DIRECTION of the force.
Force
Motion
 Calculated using the equation:
 Force x Distance  F x d
 Units  Newton x meter  N·m Joules (J)
Was work done?
 Marla pushes a box across the hall.
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–
–
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Was a force applied?
Did the object move as a result of that force?
Did the movement go in the direction of the force?
Yes to all Work Was Done
 Marla carries a box across the hall.
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–
–
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Was a force applied?
Did the object move as a result of that force?
Did the movement go in the direction of the force?
Yes, No, No Work was not done
HOW MUCH WORK?
 A man applies a
force of 500 N to
push a truck
through a distance
of 100m. How
much work does he
do?
500 x 100 : 50,000 Joules
Now how much?
 Suppose you lift a 75 N
bowling ball 2 m off the
floor. How much work
do you do?
75 x 2 = 150 Joules
One more time
 How much work is
required to lift two
50 N bowling balls
1 m off the floor?
(50 + 50) x 1 = 100 Joules
Now your turn to practice
 Please place some yarn around your book.
Make sure it is tied.
 Place the yarn on the spring scale hook.
 Pull the book slowly across the table using
the spring scale. (This measures force)
 Measure the time it took you to pull the book
and measure the distance the book traveled.
 You can now calculate work and power.
Write all data in your journals.
Thank you 
 Your work is done here today.
 You will complete a worksheet on the
meaning of work in class tomorrow.