Simple Machines 🧪 Flashcards
(26 cards)
What is work?
The amount of energy required to move an object in the direction of a force.
How do you calculate work?
Work = force X distance
Why is the work done by a machine (output) always less than work put into the machine (input)?
The machine (work output) always does less work than you (work input) because some of your work is used to overcome friction.
What is power? Give 2 examples of how to increase power.
Power is the rate (how fast) at which work is done. There will be more power if you do more work or take less time.
How do you calculate power.
Power = work
————-time
What are the units for the following:
Work:
Force:
Distance:
Time:
Mechanical advantage:
Power:
Work: Joules
Force: Newtons
Distance: Meters
Time: Seconds
Mechanical advantage: None
Power: Watts
Why do we use machines? (What does it mean to make work easier?)
Machines make work easier by changing the size or direction of a force.
Is output force always greater than output distance?
No. The force/distance tradeoff states that a machine can have more output force or more output distance but never both.
How does an inclined plane make work easier?
You get to use less force.
How does a class 1 lever make work easier?
Changes the direction of the force and the loser the fulcrum to the load the less force is needed.
How does a class 2 lever make work easier?
Move with less force.
Third class lever make work easier?
Transfers lots of momentum or moves a load a great distance.
Diagram a 1st class lever, give examples.
Input (effort) Fulcrum Load (Output)
seesaw, scissors
Diagram a 2nd Class lever , give examples
Fulcrum Load (output) Input (effort)
wheelbarrow, nutcracker
Diagram a 3rd Class lever , give examples
Fulcrum Input (effort) Load (output)
bat, spoon, broom
What is a wedge? Give examples and tell how it makes work easier.
A wedge is a double inclined plane that moves. It is used to separate or divide objects. you get more force and change the direction of the force Knives, scissor blades, axe head
What is a screw? Give examples and tell how it makes work easier.
A screw is an inclined plane wrapped around a solid core. The closer the threads are the more force you get. Examples: screws, jar lids
What is a wheel and axle? Give examples and tell how it makes work easier.
A wheel and axle consists of two objects of different sizes, one turns the other transferring work. If you turn the larger object (wheel) you get more force. If you turn the smaller object (axle) you get more distance and momentum. Examples: door knob, screwdriver, gears
How does a fixed pulley make work easier?
A fixed pulley is a grooved wheel with a rope that is attached to a permanent structure. It only changes the direction of the force.
How does a movable pulley make work easier?
A movable pulley moves with the load. you get more force.
What is a block and tackle system and how does it make work easier?
A block and tackle system is 2 or more pulleys working together. The more pulleys there are the greater the MA (you get more force).
What is a compound machine? Give an example.
A compound machine are any 2 or more simple machines joined together to do work. Scissors, block & tackle pulleys, hole punch, stapler
What is mechanical advantage?
Mechanical advantage tells how much the input force is changed.
MA > 1 means you get more force
MA < 1 means you get momentum/more distance
MA = 1 means you change direction
How do you calculate mechanical advantage?
MA = OF
IF
