INCOMPLETE Grade 8 Unit D Test (Section 1) Flashcards
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What is a machine?
A device that helps us do work
What is a simple machine?
A tool or device made of one basic machine
What are the 6 simple machines?
Levers, pulleys, inclined plane, screw, wedge, and wheel and axle
What is a lever?
A rigid bar or plank that rotates on a fixed point called a fulcrum or pivot
What is a lever used for?
Reducing the force needed to move a larger load
What are the types of levers?
First class, second class, third class
What is a first class lever?
A lever in which the fulcrum is in the middle and where the effort is on one side and the load is on the other
What are some examples of a first class lever?
A seesaw, scissors, and pliers
What is a second class lever?
A lever in which where the load is in the middle, the effort on one side, and the fulcrum is on the other side.
What is an example of a second class lever?
A wheelbarrow, a nutcracker, and a bottle opener
What is a third class lever?
A lever in which the force is in the middle, the fulcrum is on one end, and the load is on the other end
What is an example of a third class lever?
Hammer, hockey stick, rake
What is an inclined plane?
A simple machine made up of a flat surface at an angle to another flat surface
What are inclined planes used for?
Inclined planes are used to lift heavy objects with a smaller force but he force is exerted over a larger distance
What are some examples of inclined planes?
Ramps, a slanted roof, a slanted driveway
What is a wedge?
A simple machine similar in shape to an inclined plane but is forced into an object
What are some examples of a wedge?
An axe, a door wedge, a knife
What is a screw?
A cylinder with a groove cut in a spiral on the outside. Can penetrate materials with relatively small force, they can move materials slowly (cement truck)
What are some examples of a screw?
A screw (used in building), a light bulb, and a bottle cap
What is a pulley?
A system of a wire, rope or cable moving on a grooved wheel. It is used to lift objects while the operator is pulling down
What are some examples of a pulley?
Cranes, flag poles, and window blinds
What is a wheel and axle?
A combination of two attached wheels of different diameters that turn together
What are some examples of a wheel and axle?
Car tires, a bicycle, a ferris wheel
What are complex machines?
Systems where simple machines work together
What is a system?
A group of parts that work together to perform a general function
What is a subsystem?
A smaller group of parts in a complex machine that perform a specific function. Normally has a simple machine
What is linkage?
A belt or chain that transfers energy from and energy source to an object
What is transmission?
Basically linkage but only for transferring the energy from the engine to the wheels of large vehicles.
How do gears work in transmissions?
On low gear, the wheels rotate slower than the engine does. On high gear, the wheels rotate faster than the engine does.
What are gears?
A pair of wheels with teeth that interlink. When one rotates, it transfers turning motion and force to the other. . They control the transfer of energy in a system.
