Notes

W O R K
- Work: Occurs when a force exerted on an object causes that object to move some distance; is equal to force times distance and is measured in joules.
- force applied over a distance
- motion has to be same direction as the force or vise versa. If they are not in the same direction no work is done.
- two directions = it doesn't have to be exactly the same direction just a long the lines but if you turn around then it's different
- work equation = Force* Distance
- Force = newton
- distance = meter
- 1 Joule = 1 newton meter (force and motion combined)
1NM
F: 40 Newtons
Distance: = 2 meters
Formula: Force * distance
Work = 80J
- work and energy - work TRANSFERS energy

P O W E R
- Power = work/time
- Power: The rate at which one form of energy is transferred into another; the rate at which work is done.
- J/s = Jeules per second
- Power and energy - rate at which energy is transferred

V O C A B
input force - Force exerted on a machine.

output force - Force exerted by a machine.
lever-age - Number of times the input force is multiplied by a machine; equal to the output force divided by the input force.

efficiency - Equals the output work divided by the input work; expressed as a percentage.

simple machine - A machine that does work with only one movement; includes the inclined plane, wedge, screw, lever, wheel and axle, and pulley.

compound machine - Machine made up of a combination of two or more simple machines.

inclined plane - Simple machine that is a flat surface, sloped surface, or ramp

wedge - Simple machine consisting of an inclined plane that moves; can have one or two sloping sides.

screw - Simple machine that is an inclined plane wrapped around a cylinder or post.

lever - Simple machine consisting of a rigid rod or plank that pivots or rotates about a fixed point called the fulcrum.

wheel and axle - Simple machine made from two circular objects of different sizes that are attached and rotate together.

pulley - Simple machine made from a grooved wheel with a rope or cable wrapped around the groove.


U S I N G M A C H I N E S
- machines purpose is to make work easier for us. (2 diff ways they make it easier. input force and output force)
- if I increase my force that it's a mechanical advantage.
- Mechanical Advantage Formula - output force (F out) / input force (F in)
- wanna make a machine more efficient you decrease the friction.

Q & A
- How are machines designed to make work easier?
- Machines make work easier because output force of the machine can be greater than the input force.
- Explain why tin snips, designed for cutting metal, have long handles and short blades.
- The mechanical advantage for scissors, a first-class lever, is the length of the handle divided by the length of the blade. Cutting hard materials requires a high mechanical advantage.
- Explain how your teeth work as a wedge.
- A wedge changes the direction of applied force. When you push your teeth into an apple the downward effort force is changed to a sideways force that pushes the apple apart.
- Why is it important to have plenty of oil in a car’s engine?
- The oil decreases friction in the engine. This increases efficiency. It also prevents the engine from becoming damaged due to overheating from the heat generated by friction.
- How does low air pressure in bicycle tires reduce the efficiency of a bicycle?
- Low air increases the friction between the tire and the road. This reduces efficiency.

S I M P L E M A C H I N E S
- A list of simple machines: inclined plane,lever,wheel and axle, screw, wedge, and pulley.
- a compound machines is basically adding more than one simple machine together.
- inclined plane is basically a ramp
- fulcrum is the pivot point
- two diff types of pulleys: fixed pulleys and movable pulleys.
- fixed pulleys: help us change the direction
- movable pulleys: can increase our mechanical advantages.