6th Grade Ch 3 Work And Machines Flashcards
What is work?
Work is done on an object when the object moves in the same direction in which the force is exerted.
What is a simple machine?
A simple machine is a machine that makes work easier.
What is a compound machine?
A compound Machine is a machine that combines two or more simple machines| Within a compound machine, the output force of one simple machine becomes the input force of another simple machine.
Lever
A lever is a rigid bar that is free to pivot, or rotate, on a fixed point| 1st, scissors and seesaws| 2nd, doors and bottle openers| 3rd: spoons, shovels, baseball bats|
Pulley
A simple machine that consists of a grooved wheel with a rope or cable around it that is used to pull something up or down with less work needed| An example is raising a sail on a sailboat
Wedge
A device that is thick at one end and tapers to a thin edge at the other end| An example is pulling up a zipper
Fulcrum
The fixed point that a lever pivots around| An example is a prism
Wheel and Axle
A simple machine made of two connected objects that rotate about a common axis| screw driver, car
Screw
A screw is an object that orbits around another object in space
What is power?
The rate at which work is done| Power equals the amount of work done on an object in a unit of time.
What is power measured?
Power equals work divided by time
What is force?
A push or pull exerted on an object.
What is efficiency?
It compares output work to input work by percentage, the higher the percentage, the more efficient the machine is.| To calculate the efficiency of a machine, divide the output work by the input work and multiply the result by 100 percent.
Which body parts act as simple machines?
Wrist, elbow, knee, neck, shoulder, foot, teeth
What is mechanical advantage, and how is it calculated?
The number of times a machine increases a force exerted on it| the ratio of output force to input force is the mechanical advantage of the machine| Mechanical Advantage equals output force divided by input force
