Science Unit D Flashcards
A machiene
A device that helps us do work.
A simple machiene
is a tool or device made up of one basic machine
How many simple machines are their?
There are six simple machines that help us do work: the lever, inclined plane, wedge, screw, pulley, and wheel and axle.
Lever
The lever is a rigid bar or plank that can rotate around a fixed point called a pivot or fulcrum. Levers are used to reduce the force needed to carry out a task such as pulling a nail, opening a bottle, hitting a baseball, and cutting paper
First class lever
A first-class lever has the fulcrum between the load and the point where the effort is exerted to move the load.
A second class lever
A second class lever has the load between the effort and the fulcrum.
A third class lever
A third class lever has the effort between the load and the fulcrum.
Inclined plane
An inclined plane or ramp would make it easier for you to move the box up onto the desk. An inclined plane makes it possible to lift heavy objects using a smaller force.
Wedge
A wedge is similar in shape to an inclined plane, but it is used in a different way. The wedge machine is forced into an object. By pressing on the wide end of the wedge, you can exert a force on the narrow end so it splits an object apart.
Screw
A screw is a cylinder with a groove cut in a spiral on the outside. Using a screw helps you increase the force you use. It can penetrate materials using a relatively small force. A screw can also be used for converting rotational (turning) motion to linear motion (motion in a straight line).
Pulley
A pulley consists of wire, rope, or cable moving on a grooved wheel. Pulleys may be made up of one or many wheels and can be fixed in place or movable. They can be linked together in systems for moving and lifting objects
Wheel & Axl
The wheel and axle are a combination of two wheels of different diameters that turn together. A longer motion on the wheel produces a shorter but more powerful motion at the axle. The steering wheel and steering column in a car together form a wheel and axle. That combination is one example of using a wheel and axle to increase the size of a force
Complex machine
Most of the devices that we use today are made up of several simple machines. These devices are called complex machines. A complex machine is a system in which simple machines all work together
System
A system is a group of parts that work together to perform a function.
Subsystem
Within the bicycle are groups of parts that perform specific functions, such as braking or steering. These groups of parts are called subsystems. They consist of 1 simple machine
Linkage
The linkage is the part that transfers your energy from the pedals to the back wheel. In a bicycle, the chain is that linkage.
Transmission
Most machines that move objects are more complex than a bicycle. They usually move much larger loads than just one person. These machines use a special type of linkage called a transmission to transfer the energy from the engine to the wheels
Gears
Gears are essential components of most mechanical systems. They consist of a pair of wheels that have teeth that interlink. When they rotate together, one gearwheel transfers turning motion and force to the other
mechanical advantage
The mechanical advantage of a machine is the amount by which a machine can multiply a force.
Input force
The force applied to the machine is called the input force
Output force
The force the machine applies to the object is called the output force
Calculating mechanical advantage
MA = Output force/input force
Speed ratio
A measure of how the speed of the object is affected by a machine is called the speed ratio
Calculating speed ratio
SR = Input distance/output distance
Friction
Friction is a force that opposes motion. Friction is caused by the surface roughness of materials. A rough surface creates more friction than a smooth one
Efficiency
Efficiency is a measurement of how well a machine or device uses energy
Calculating efficiency
E = Mechanical advantage/speed ratio times 100
Work
work is done when a force acts on an object to make the object move
Calculating work
W = F times D W = Force times Distance
Pressure
pressure is a measure of the amount of force applied to a given area
