WORK
Work is the the product of force and distance
work= force X distance
w=fxd
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Work is a Scalar quantity
The SI Unit of force is the Newton (N)
The SI Unit for distance is the meter (m)
The SI Unit for work is the Joule (J)
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1 Newton X meter = 1 Joule
Work Requires Both FORCE and MOTION
w=fXd
f = w/d
d = w/f
Power
Power is the rate at which work is done.
-Rate: any measurement over a period of time
-mph
-m/s
-Power is the amount of work that is completed in a given time
Power = work/time
p = w/t
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Power is measure in Joules per second (J/s)
SI Unit of power is the watt (W)
Power requires work! No work = no power
Simple Machines
Simple Machines: the simplest, least complex devices that use leverage to do work by multiplying a
force.
There are 6 simple machines
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Lever
Inclined Plane
Wheel and axle
- wedge
- screw
- pulley
There are two basic parts to a simple machine
1. Input Force: Often referred to as the Effort
2. Output Force: Often referred to as the Load
Kinetic Energy
The Energy of Motion!!
There are 2 factors that determine kinetic energy: Speed and Mass
Potential Energy
Potential energy: a type of energy that has the ability to be used to do some work, but it
is being stored for later
Types of Potential Energy:
Elastic - think springs
Chemical - chemical processes, food, etc.
Nuclear - I think we are all aware of this potential energy source
Electric - protons and electrons in an electrical field
Gravitational ( Most Commonly Considered)
Work
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Unit: Joule (J) = 1N x m = 1kg x m2/s2
Power
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Unit: Joules/second or J/s = Watts (W)
Mechanical advantage
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Input:
Efficiency
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Ideal mechanical advantage of machines
Lever
Pulley
Wheel and axle
Wedge
Incline plane
Screw
Total IMA of a compound machine
● Find the total IMA of each machine, then multiply
○ Example: What is the mechanical advantage of a compound machine
composed of an inclined plane that has a 6 m ramp with a height of 1 m
and a movable pulley with two supporting rope sections?
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Kinetic energy
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Potential energy
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Mechanical Energy
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or
when dealing with springs