Presentation on theme: " A simple machine has few or no moving parts. Simple machines make work easier. With or without a simple machine the work is the same. Also when."— Presentation transcript:
A simple machine has few or no moving parts. Simple machines make work easier. With or without a simple machine the work is the same. Also when simple machines are combined they can make complicated bigger machines. OK Go Music Video Rube Goldberg Creation OK Go Music Video Rube Goldberg Creation
A wheel axle is a simple machine made of two circular or cylindrical objects that are fastened together and that rotate about a common axis. The object with larger diameter is the wheel. The object with the shorter diameter is the axle.
With a screwdriver the handle is the wheel and the shaft is the axle Every time you turn a door knob, you are using a wheel and axle. The knob is the wheel and the shaft is the axle. The steering wheel of a car is also another example.
A Pulley is a grooved wheel with a rope, or a chain, or even a steel cable wrapped around it. You use a pulley by pulling on the rope. As a result, you can change the amount and direction of your input force.
Garage Doors are one of the most common pulley systems. Elevators also use the pulley system.
An inclined plane is a flat surface that is higher on one end Inclined planes make the work of moving things easier.
Inclined planes are always used on moving trucks or trucks that have to carry a lot of weight. Some roads also are slanted like inclined planes.
A wedge is a device that is thick at one end and tapers to a thin edge at the other end. It might be helpful to think of a wedge as an inclined plane (or two inclined planes back to back) that can move.
Examples of wedges are knifes, axes, and zippers. Sometimes lumberjacks will place wedges in tree’s when they are cutting them down it makes it easier.
A screw is an inclined plane wrapped around a shaft or cylinder. The inclined plane allows the screw to move itself when rotated.
The Lever a rigid bar that is free to turn about a fixed point called the fulcrum Every Lever has three (3) parts: 1. Resistance Force, Input Force or Load, What you are trying to move or lift. 2. Effort Force or Output Force - The work done on the Lever. 3. Fulcrum – A fixed pivot point.
When the fulcrum is closer to the effort than to the load: there is a loss in force
When the fulcrum is closer to the load than to the effort: There is a gain in force.
When the fulcrum is midway between the effort and the load: there is no change in force
Examples: Seesaw Crowbar Scissors
If the size of scissors is increased than the amount of force exerted on their tip would be decreased.
Using a lever is important because it reduces the amount of force needed to lift an object.
The load is between the effort and the fulcrum. The fulcrum is at one end of the lever. The fulcrum is usually closer to the load. Produce a gain in force.
The effort is between the load and the fulcrum. There is usually a loss in force, but a gain in speed and distance.
Examples: Broom Shovel Fishing rod
Simple Machines can be put together in different ways to make complex machinery. This machinery where you use simple machines is now known as a compound or complex machine. Rube Goldberg Website Rube Goldberg Website
How much easier and faster a machine makes your work is the mechanical advantage of that machine. In science terms, the mechanical advantage is the number of times a machine multiplies your effort force. Mechanical Advantage is equal to the Effort Arm Distance divided by the Resistance Arm Distance. If you place the effort arm two meters away from the fulcrum and the resistance two meters away from the fulcrum, what is the mechanical advantage? Distance is measured in cm or meters
Increasing the distance of the effort arm while decreasing the distance of the resistance arm allows you to gain more "power." There is, however, the challenge that you cannot make the effort arm too long or it is too hard to use! Which Smiley Face would be easier to move? Lever Website Lever Website
The Mechanical Advantage of a Lever can also be calculated by using the forces. MA=Resistance Force divided by the Effort Force You apply a force of 18 N on to the end of a lever to open a paint can lid. The resistance of the lid is 9 N. Calculate the MA. Force is measured in Newton's. (N)
How could you increase the mechanical advantage of this lever? Move the Fulcrum closer to the weight by doing so you increase the effort arm’s length! By doing so you extend the effort arm.
Four levers were built and the effort measured as they lifted the same object. The effort for each is listed below: Lever A 0.5 kg Lever B 1 kg Lever C 2 kg Lever D 4 kg Which lever has the greatest mechanical advantage? AA
Two levers were built and the effort measured as they lifted a 2 kg object by 10 cm. The effort for each is listed below: Lever A 2 kg Lever B 4 kg Which lever did the most work? They did the same amount of work.
Which drawing shows a lever that would need the least effort force to lift the weight? The second drawing because the fulcrum is closest to the load!
Work is done on an object when an applied force moves it through a distance. In our everyday language, work is related to expenditure of muscular effort, but this is not the case in the language of physics. A person that holds a heavy object does no physical work because the force is not moving the object through a distance. Work, according to the physics definition, is being accomplished while the heavy object is being lifted but not while the object is stationary. The amount of work is calculated by multiplying the force times the displacement. That formula looks like this: W = F * d
Passing man (A) slips on banana peel (B) causing him to fall on rake (C). As handle of rake rises it throws horseshoe (D) onto rope (E) which sags, thereby tilting sprinkling can (F). Water (G) saturates mop (H). Pickle terrier (I) thinks it is raining, gets up to run into house and upsets sign (J) throwing it against non- tipping cigar ash receiver (K) which causes it to swing back and forth and swish the mop against window pane, wiping it clean. If man breaks his neck by fall move away before cop arrives.
Open window (A) and fly kite (B). String (C) lifts small door (D) allowing moths (E) to escape and eat red flannel shirt (F). As weight of shirt becomes less, shoe (G) steps on switch (H) which heats electric iron (I) and burns hole in pants (J). Smoke (K) enters hole in tree (L), smoking out opossum (M) which jumps into basket (N), pulling rope (O) and lifting cage (P), allowing woodpecker (Q) to chew wood from pencil (R), exposing lead. Emergency knife (S) is always handy in case opossum or the woodpecker gets sick and can't work.
As you walk past cobbler shop, hook (A) strikes suspended boot (B), causing it to kick football (C) through goal posts (D). Football drops into basket (E) and string (F) tilts sprinkling can, (G) causing water to soak coat tails (H). As coat shrinks, cord (I) opens door (J) of cage, allowing bird (K) to walk out on perch (L) and grab worm (M) which is attached to string (N). This pulls down window shade (O) on which is written, "YOU SAP, MAIL THAT LETTER." A simple way to avoid all this trouble is to marry a wife who can't write.
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