of Simple Machines
of Simple Machine
stiff bar that turns on a point, called the fulcrum. A lever trades
distance for force or force for distance, that means you use less
force over a greater distance or more force over a shorter distance.
crowbar, claw hammer, bottle opener examples
lever has 3 parts:
Force or Load, or What you are trying to move or lift.
2. Effort Force or The Work done on the Lever.
3. Fulcrum or A fixed pivot point
There are different
kinds of levers depending on the placement of the fulcrum:
The fulcrum can be between the force and what you want to move.
The fulcrum can be at one end, the force at the other end, and what
you want to move in the middle. (bottle opener)
The fulcrum can be at one end, the force in the middle, and what
you want to move at the other end. (tennis racquet)
levers are put together like scissors and pliers. The
Elements of Machines .
Follow a modern
team as they build a medieval
weapon, then play "Destroy
sloping surface, such as a ramp, used to lift heavy loads with little
effort. The inclined plane does not move. It works by allowing less
force but over a greater distance. More...
ladder, stairs, escalator Examples
inclined plane and rollers were used in building the Pyramids in
Egypt. Ramps over one mile long were used to move and place 2.5
million limestone blocks weighing up to 70 tons each.
plane that tapers to a sharp edge A wedge is really two inclined planes
joined back to back. A wedge changes the direction of the force. A
wedge moves. More...
chisel, knife, saw, ax, doorstop, pins examples
Wedges can be
forced between two things to hold them tightly together, like nails
or a doorstop. A knife or a pin is a sharpened wedge.
-a wheel connected
to a rigid rod. It can be used to increase force and to increase
are special kind of Wheel and Axle.
knobs, car wheels , water faucets, airplane propeller, pedals on a
door knob uses a larger "knob" to turn a smaller rod. You
trade distance for force. In a bicycle you trade force for distance.
By turning the bicycle axle with a pedal you get more distance (or
speed) as the larger wheel turns.
-a small wheel
with a grooved rim that holds a rope. A fixed pulley changes only
the direction of the force but not the force, distance or speed.
a curtain or mini-blind, lifts a flag on a flag pole,
of lifting up, you can pull the rope down and lift the load down using
your body weigh. A pulley is also wheel that turns around an axle.
inclined plane wrapped around a cylinder. The threads of a screw form
a tiny "ramp" that goes around the screw. A screw allows
you to use less force, and it changes the direction of the force.
grinder, jar and lid, piano stool, helicopter blade, boat propeller
and bolts ( a type of screw) allow you to fasten things together.
Almost every machine built has some form of screw to fasten it together.
tools have two or more simple machines working together. For example:
scissors are 2 levers joined at fulcrum AND the blades are wedges.
A can opener is a lever and a wedge. Can you think of more?