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How Machines Do Work (Pgs. 114-121) (Mechanical advantage (Increasing…
How Machines Do Work (Pgs. 114-121)
What is a machine
A machine makes work easier by changing at least one of three factors. A machine may change the amount of force you exert, the distance over which you may exert force, or the direction in which you exert force
Input and output Forces
Input Force
The force you exert onto the machine
Output force
The Force the machine exerts on an object
Input and Output Work
Output Work
Input Force * Input Distance = Input Work
Input Work
Output Force * Output Distance = Output Work
Change In Machines
Changing Distance
In some machines the output force is less than the input force, an example is a hockey stick, this is useful cause the end of the stick would move a farther amount from less movement made by your hands
Changing Direction
Some machines just don't change either their force or distance, and example of this is a weight machine, because you have to use an equal force to pull up an equal weight, to build muscle.
Changing Force
In some machines the output force is greater than the input force, an example of this is a ramp, cause lets say your lifting the box up stairs, or your rolling it up a ramp, which is easier, right its the ramp
Mechanical advantage
Increasing force
When the output dorce is greater than the input force, the mechanicle advantage of a machine is greater than 1
a machines mechanical advantage is the number of times a machine increases a force exerted on it, Mechanical advantage = Output Force/Input Force
Increasing Distance
For a machine that increases distance, the output force is less than the input force, so the mechanical advantage is less than 1
Changing Direction
If only the direction changes the input force will be the same as the output force, the mechanical advantage will always be 1
Efficiency of machines
In real situations, the output work is always less than the input work
Friction and Efficiency
The efficiency of a machine compares the output of work to the input of work
Calculating Efficiency
To calculate the efficiency if a machine, divide the output work by the input work and multiply the result by 100 percent
Real and Ideal Machines
No machine can be 100% efficient because of friction causing lower efficiency, a machines measured mechanical advantage is called actual mechanical advantage