Machines
Mechanical Advantage
Mechanical Efficiency
Vocabulary
Math
100
What is a machine?
A device that makes work easier.
100
How do you find mechanical advantage?
Output Force divided by Input Force.
100
How do you calculate mechanical efficiency?
Output work/Input work x 100
100
What is the work done on a machine?
Work input
100
What is the mechanical advantage if you use 70N to make a machine exert 245N?
3.5
200
What are the two ways a machine can make work easier?
Changing the direction of the force. Changing the size of the force.
200
Which is better, a machine with a mechanical advantage of 3 or 8?
8
200
How do you label mechanical efficiency?
Percent (%)
200
What is a machine that has 100% efficiency called?
Ideal Machine.
200
What is the output force of a machine with a mechanical advantage of 5, if you use 45N of force?
225N
300
What are three examples of machines?
Scissors, knife, screwdriver, pencil sharpener, car,...
300
If you push with 20N to move a 300N desk up a ramp, what is the mechanical advantage of the ramp?
300/20 = 15
300
Why can't a machine have 100% efficiency?
Friction.
300
What is the number that tells you how many times a machine multiplies force?
Mechanical Advantage
300
What is the input force of a machine that has a mechanical advantage of 2 and exerts a force of 35N?
17.5N
400
True or False: Machines increase the amount of work done.
False.
400
What are the units for mechanical advantage?
There are no units.
400
What is the mechanical efficiency if it takes 30J of work to make a machine do 20J of work?
20/30 x 100 = 66.7%
400
What is the ratio of work output to work input?
Mechanical Efficiency
400
Machine A uses 40N of force when you push with 30N. Machine B uses 50N of force when you push with 40N. Which machine has a better mechanical advantage?
Machine A
500
How does a machine lower the size of a force needed?
Increasing the distance.
500
What does it mean if the mechanical advantage is less than one?
The machine lowers the force and increases the distance.
500
What do we use to lower friction and increase a machine's efficiency?
Lubricants.
500
What is a machine?
A device that helps do work by changing the size or direction of a force.
500
If I push with 5N over 0.52m on a lever and the lever pushes with 15N over 0.11m, what is the mechanical efficiency?
63.5%
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