Machines Flashcards
What is a simple machine?
A basic mechanical device for applying force and changing either its size or direction
What are some
different types of simple machines?
Levers, ramps, pulleys
What is a lever?
A rigid bar that moves around a fixed point so one end can be pushed or pulled to move the other 2nd with a greater or smaller force
What are the four characteristics all levers have?
1) They have a fixed point called a fulcrum
2) The lever pivots around a fulcrum
3) An effort force is applied to the lever
4) the effort force is transferred by the lever to exert a load force that moves or pushes the load
What is a class 1 lever?
A lever in which the fulcrum is between the load and effort.
A class 1 lever is a force multiplier because they are able to magnify the effort force you put in.
Example of a class 1 lever is a crowbar.
What is a class 2 lever?
A lever in which the fulcrum is at one end and the load is between the fulcrum and the effort.
Class 2 levers are force multipliers because they magnify the effort you put in.
An example is a wheelbarrow or bottle openee.
What is a class 2 lever?
A lever in which the fulcrum is at one end and the load is between the fulcrum and the effort.
Class 2 levers are force multipliers because they magnify the effort you put in.
An example is a wheelbarrow.
What is a class 3 lever?
A lever in which the fulcrum is at one end and the effort is between the fulcrum and the load.
Class 3 levers are speed multipliers (not force multipliers). A speed multiplier increases the speed of an object.
An example of a class 3 lever is a tennis racquet.
What does effort mean?
It is the input force to a simple machine
You calculate it by dividing load force by mechanical advantage
What is the load?
It is the object that needs to be moved?
What is the fulcrum?
It’s the point in a lever where a bar is supporter; the lever turns about this point.
What is the mechanical advantage?
It is the ratio of the output force to the input force.
You calculate it like this
How do you measure distances to a fulcrum?
What is a force multiplier?
It’s something that increases the size of the force.
What is a speed multiplier?
It’s something that increases the speed of an object.
What is a ramp?
It is an inclined surface connecting a higher and lower level.
It is used to move heavy objects against the force of gravity.
A ramp provides a mechanical advantage by requiring a smaller effort force to push an object up a ramp that it would to lift it straight up.
What ramps have the greatest mechanical advantage?
Ramps that are less steep have a greater mechanical advantage.
What ramps have the greatest mechanical advantage?
Ramps that are less steep have a greater mechanical advantage.
Besides a ramp, what are other examples of inclined planes?
A screw.
What is a wedge?
A wedge is a simple machine with two inclined planes.
It changes the direction of force and multiplies it.
Examples of wedges are axe heads, door stops, pointed ends of nails and pins.
Wedges that are longer and thinner have higher mechanical advantages than ones that are shorter and fatter.
What is a pulley?
A pulley is equipment consisting of a grooved wheel (or wheels) with a rope or chain attached to an object to move it.
Does a single pulley (one wheel) decrease the effort needed to lift the object?
No. It only changes direction if the force. It is easier to pull down on a rope than lift something up because you can put your weight into it.
How do you decrease the effort force needed to lift an object?
Add more pulleys. The more pulleys you add the higher the mechanical advantage.
What does it mean if a pulley has a mechanical advantage of 2?
It means it takes half the effort to lift an object compared to if a pulley was not used.
But you will need to pull the rope twice the distance to lift the load.
How did you calculate mechanical advantage of a pulley?
Study this
See picture
What is a gear?
A device consisting of connecting set of wheels with teeth.
What is a cog?
One of the tooth like parts around the edge of a wheel
What is a driving gear?
The gear connected to source of force
What is the driven gear?
The gear that rotates due to the rotation of the driving gear.
What type of gears are speed multipliers?
When driving gear is bigger because the driven gear turns more times
Example: egg beater
What type of gears are force multipliers?
When the driving gear is smaller than driven gear.
Example: mountain bikes
