simple machines

friction

force between two surfaces touching trying to opposes movement or attempted movement together. Slows or stops movement.

simple machine

: A device that makes work easier by changing the size or direction of a force.reducing the effort needed, changing the direction of a force, or increasing speed/distance.

mechanical advantange

is a measure of how much a machine multiplies the input force you apply to it.

what is a load fulcrum and effort

Fulcrum: The fixed point around which a lever pivots. Load: The object or resistance being moved. Effort: The force applied to a machine

lever

a simple machine that consists of a bar that pivots at a fixed point called a fulcrum

first class levers

Effort — Fulcrum — Load eg seesaw

second class

Fulcrum — Load — Effort eg wheelbarrow

third class

Fulcrum — Effort — Load eg tweezers

mechanical advantage of levers

effort to fulcrum / load to fulcrum

mechanical advantage

load/ effort

inclined plane

An inclined plane is a sloping surface

allows a load to be moved to a higher or lower position

uses less effort but a longer distance

mechanical advantage of inclined plane

length of slope/ height of slope

wheel and axel

two circular objects of different sizes that are attached in such a way that they rotate together

different types of wheel and axel

screw driver:

doorknob:

ferris wheel:

ceiling fan:

Pulley

helps lift or move objects by changing the direction of the applied force

fixed pulley

is attached to the supporting stucture and stays inplace

moveable pulley

is able to move with the object being lifted

compound pulley

when 2 or more pulleys are put together

mechanical advantage of a pulley

load / pulling effort ( the mechanical advantage is usually the amount of pulleys)

gears

wheels with teeth

transfers force and motion.

always a driver and a driven wheel

spin in oppisite directions

gear ratio

teeth on driven : teeth on driver

driver & driven

The input gear — the gear receiving the force. The output gear — the gear being moved.

wedge

A wedge is two inclined planes stuck together.

diffrerent wedges

axes, knifes and nails

screw

A screw is an inclined plane wrapped around a cylinder.

parts of a screw

Head → the part you turn or push . Pitch → distance between each thread.

mechanical advantage of a screw

circumference/pitch

friction increases with

Rougher surfaces More force pressing surfaces together

friction decreases with

Smoother surfaces Wheels/ball bearings

useful friction

Walking Braking a bicycle Writing with a pencil Gripping objects

unwanted friction

Machines wearing out Parts heating up Making machines less efficient

examples of a inclined plane

ramps, escalators, conveyor belts

relationshipe between gear size and rotational speed

A smaller gear rotates faster,

then larger gear rotates slower.

how do levers make work easier

changing the size, speed, or direction of a force

How does a wheel and axle make work easier?

reducing the effort needed to move or lift an object. The larger wheel gives you more turning force.

Identify the parts of a pulley and explain how it works.

wheel, groove, axle and rope. The rope runs around the grooved wheel. A pulley changes the direction of a force ans reduce the effort needed to lift a load.