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
4.
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
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
12.
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
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.