This document discusses simple machines and their uses. It defines six types of simple machines: lever, pulley, wheel and axle, inclined plane, screw, and wedge. For each machine it explains how it works and provides examples. It also covers concepts like work, energy, power, mechanical advantage, efficiency, and how machines conserve energy. Simple machines allow us to do work more easily by reducing the amount of force needed.

1. Chapter 5
Simple machines

2. WORK
 The transfer of
energy that occurs
when a force makes
an object move
 In order for work to
be done a force must
make an object move

3. 2 Conditions of work
 1. The object must move
 2. Movement must be in the same direction as
the force applied

5. Work and Energy
 When work is done there is always a transfer
of energy
 Energy is the ability to do work
 When you do work on an object, you increase
its energy

6. Calculating work
 Work (J) = Force (N) x distance (m)
 W = Fd

7. Power
 The rate at which work is done
 SI unit for power is the Watt (W)
 P (watts) = Work (J)/Time (s)
 Usually expressed in kilowatts

8. Power and Energy
 Power is the rate at which energy is transferred
 Power (w) = energy (J)/Time (s)

9. Machine
 A device that makes doing work easier

10. Simple Machines
 A Machine that does
work with only one
movement of the
machine
 6 types of simple
machines: lever, pulley,
wheel and axle, inclined
plane, screw, and wedge

11. Lever
 A bar that is free
to pivot or turn
around a fixed
point
 The fixed point is
called a fulcrum
 There are 3
classes of levers

13. Pulley
 A grooved wheel with a
rope, chain, or cable
running along the
groove
 The axle of the pulley
acts as the fulcrum
 Fixed and movable
 Fixed IMA = 1,
Movable IMA = 2

14. Block and Tackle pulley
 A system of pulleys
consisting of both fixed
and movable pulleys
 IMA is equal to the
number of rope
segments that support
the weight

15. Wheel and Axle
 consists of a shaft or
axle attached to a larger
wheel.
 The wheel and axle
rotate together
 Examples: Pencil
sharpeners, door knobs,
screw drivers, faucet
handles

16. Inclined Plane
 A sloping surface, such
as a ramp.
 Reduces the amount of
force required to do
work
 IMA = Length of slope
(m)/Height (m)

17. Screw
 An inclined plane
wrapped in a spiral
around a cylindrical
post
 IMA is related to the
spacing of the threads

18. Wedge
 An inclined plane with
one or two sloping sides
 It changes the direction
of the input forces

19. Compound Machine
 Two or more simple machines that operate
together
 A car is a compound machine

20. Compound Machines

21. 2-Forces Involved in Work
1. Input Force: The force that is applied to the
machine. (effort force)
Given the symbol Fin
2. Output Force: The force applied by the
machine.
Given the symbol Fout

22. 2-Types of Work done on a Machine
1. Input Work: The work done by you on the
machine.
Given the symbol Win
2. Output Work: The work done by the
machine.
Given the symbol Wout

23. Conserving Energy
 A machine cannot create energy, so…
Wout can never be greater than Win

24. Which means that…
 Wout will always be less that Win …
 because friction changes some of the energy
to heat.

25. Ideal Machine
 A machine without friction.
 Win = Wout

26. Mechanical Advantage
 The ratio of the output force to the input force.
 Can be calculated using the following equation.

27. Efficiency
 A measure of how much of the input work put into a
machine is change into useful output.

28. Efficiency Cont…
• The efficiency of an ideal machine is 100
percent.
• The efficiency of a real machine is always less
than 100 percent.

29. How can machines be made more
efficient???
• by adding a lubricant,
such as oil or grease, to
surfaces that rub
together.