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## John Lisenbe

on 7 August 2013

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#### Transcript of Machines and Mechanical Advantage

Chapter 10.2
Remember! You can never get more out of a machine than you put in. So there is always a sacrifice:
If you get higher force...you lose distance.
If you get more distance...you have to pull harder.
Mechanical Advantages Greater than 1 mean the object is EASIER to lift.
Mechanical Advantages less than one mean the object is harder to lift, but it moves more.
Talk it Out
1) You are using a wench to lift a car. Would the mechanical advantage be greater than one or less than one?

2) A pulley set up is lifting a weight and has a mechanical advantage of 3. If you pull 6 feet of rope, how high will your weight be pulled upward?

3) Why do the two equations of mechanical
advantage flip (input over output then output over input)?
Every simple machine has a mechanical advantage.
Results
What does it mean for a machine to have a mechanical advantage of 1?
The mechanical advantage tells you the relationship between the input and output forces.
Examples
1) A class 2 lever is being pushed down with 40
Remember yesterday when we had two different sets of pulleys?
each pulley set required a different amount of force to complete the same task
that is because each set of pulleys had a different MECHANICAL ADVANTAGE.
Changing the mechanical advantage has two effects:
Change the input and output distance.
Change the input and output forces.
MA=
Output Force
Input Force
or
Input Distance
Output Distance
Input force=Output force
Input force is different than output force.
N of force and it outputs 75 N of force. If the
lever is 3 meters long total, at what distance
from the fulcrum is the weight placed?
2) A pulley system with a mechanical advantage
of 3 is lifting a weight that has a mass of 45 kg.
How much force does it take to lift the mass?
called the ideal mechanical advantage or IMA
You Try
1) A pulley system is set up so that it has
a mechanical advantage of 2. A 10N weight
is lifted using 8 N of force. How much
upward acceleration does the weight receive?
2) Bill is using an inclined plane to lift some
boxes onto a truck. If the boxes weigh 10
lbs and he wants to pull with only 4 lbs
of force, how long of a board should he
use to lift them into the 4 ft high truck?
Ex: Pull up a weight 2 feet by pulling 4 feet of rope.
Ex: Lift a 10 lb weight using only 5 lbs of force.
Full transcript