The Science of Work

1. The Science of Work
Mr. Ilko

2.  You are at home reading a textbook,
you read a page in the textbook and
think about how you are going to
summarizing it
 You feel like you are doing work but
according to scientific definition of
work you aren’t.
 Why is that??

4.  The thing that makes all the images
examples of work is MOVEMENT
 Work occurs only when forces act
onto an object and the object moves
 If you are holding something in place
you are not doing work, the object
must move some distance

6.  Look at the photo of the men pushing
the car in the sand
 A strong force is being exerted onto
the car, but the car is not moving
 According to the scientific definition
NO WORK is being done

7. How to Solve for Work
Work X

8.  In this formula;
◦ F = force applied
◦ d = distance the object moves in the
direction of the applied force
 Ex. If you lifted your chair above your
desk, how much work would you do?
Assume you applied a force of 50N
and lifted the chair 1.2m

9.  Force = 50N
 Distance = 1.2m
 Work = Force X Distance
50N X 1.2 M
= 60N.m J = Joule
J = Newton X meter
= 60 J

10.  The unit “J” is known as a Joule
 Named after the English Scientist
James Joule
 Joule was interested in the relationship between
work and energy
◦ Unit is used to measure energy

11. Energy and Work
 Energy and work are closely related
because without energy, there would
be no work.
 In a car, the energy to drive the
wheels comes from gasoline
◦ An energy source (gas) provides the force
to make the work (car moving) possible.

12. Work and Machines
 Using a machine does not mean that
less work is being done
 When you use a machine the same
amount of work is done, you just use
less force!!!

13. Proof
 You need to lift a student in a wheel
chair to the top of steps.
 The first student uses a ramp to move the
wheel chair 5m, and uses 320N of force.
 The second student lifts the chair 2, and uses
800N of force.
 Who uses more??

14.  1.
◦ W = Force X distance
= 320N X 5m
= 1600N.m  1600 J
2.
W = Force X Distance
= 800N X 2m
= 1600N.m  1600J

15. Friction
 Don’t forget that friction will play a role
in the actual work it takes to move an
object
 The values are not exact, all are
calculated with friction NOT being a
factor