- Количество слайдов: 52
Simple Machines Group BB
A Simple Machine: Wedge
What is a wedge? ¢ A wedge is an object with at least one slanting side and a sharp edge end. It can also: Hold an object in place l Separate two objects or portion of an object. l Lift an object. l
Calculating Mechanical Advantage ¢ ¢ A wedge is like an inclined plane, but can be moved. To calculate the mechanical advantage, divide the wedge length by its width at the thickest edge.
Changing the Force ¢ When adding force to the wide end of the wedge, it changes to perpendicular force to the inclined surface.
Example ¢ If you have a wedge that has a length of 8 inches and is 3 inches thick, the mechanical advantage of the wedge would be 2. 67
Compound Machine #1 ¢ Can Opener The actual part of the can opener that opens the can itself is made up of a wedge. l It is also made up of lever, gear, and wheel and axle. l
Compound Machine #2 ¢ Stapler The staples that go through the paper are in fact wedges. l The stapler itself is made up of levers. l
Compound Machine #3 ¢ Shovel l A Shovel is made up of two simple machines, one being a wedge, the other being a lever.
Bibliography http: //www. usoe. k 12. ut. us/curr/science/sciber 00/8 th/machines/sciber/ machine 3. htm 1. l Gives examples of simple machines that are wedges, also provides an explanation of what a wedge is. http: //www. mikids. com/Smachines. htm 2. l Gives the definition of each of the six simple machines, and shows pictures. http: //science. jrank. org/pages/4060/Machines-Simple. html 3. l This site has an in depth explanation of a wedge. http: //www. edheads. org/activities/simple-machines/ 4. l Helps understand which tools in the shed and house have simple machines, and what simple machines those tools are made up of. http: //en. wikipedia. org/wiki/Wedge_(mechanical_device) 5. l Gives the mechanical advantage of the simple machine.
Wheel and Axle By James Pesta
Wheel and Axle definition n Wheel and axle is simple machine with a cylinder on a rod that is pulled or turned by something (like a rope) to create a force. more easily
Picture of Wheel and axle
Ideal Mechanical Advantage To find the mechanical advantage you have to use this formula Example: If your axle radius is 5 inches and your wheel radius is 15 inches your mechanical advantage is 3
Force The wheel and axle changes the forces coefficient of friction by rolling instead of sliding. When a object slides it have just one surface contacting the ground and gravity is pushing down, but it an object it rolling gravity has a little less affect on it and the friction is significantly less.
Compound Machine #1 Bike-Simple Machines-screw, wheel and axel, lever, pulley
Compound Machine #2 Wheel Barrel-Simple Machines-lever wheel and axle
Compound Machine #3 Drill-Simple Machines- screw, wheel and axle, lever
Sites Dictionary. com n library. thinkquest. org/CR 0210120/Compound %20 machine. htm n wikipedia. com n science. jrank. org/pages/4059/Machines-Simple. Compound-machine. htm n edheads. org n
The Pulley By Steven Tanner Period 1
What’s a Pulley? A pulley is a wheel with a grooved rim that turns inside of a frame and serves to change the direction of or to transmit force.
Why pulleys? Pulleys are mainly used to lift heavy objects. They work by reversing the direction in which force must be applied from an upward direction to a downward one, which allows gravity to work on its user’s side. This way, objects require less force to be lifted to their proper locations.
Pulleys and Mechanical Advantage l l l Mechanical advantage is the ratio of a mechanism’s output force to its input force. Pulleys are the only simple machines in which mechanical advantage is limited to whole numbers. In the diagram to the right, the mechanical advantage is one: the force put into pulling one side of the rope or string is equal to the force pushing the other side up. Thus, the effort is equal to the load, and…
Gaining Mechanical Advantage l l MA=Load/Effort A simple way to gain the mechanical advantage is to turn the pulley upside down. Notice how there are two lengths of rope meant to pull up a single load. This means that each side of the lifting rope supports half of the load. Therefore, with the equation above, we can find that the mechanical advantage is 1/. 5=2 (You could also count how many times the rope goes over a pulley, as seen on the example). l l
Example l In the example to the right, the rope goes over a pulley five times. Therefore, this pulley system’s mechanical advantage is 5.
Crane l A crane is basically a giant system of multiple pulleys. The one shown here is small and uses only two, but some of the largest have been known to use three or ever four! In any case, the pulley will be pulled up by the string in order to lift an object into the air and move it to a new location. Cranes also use inclined planes to raise and lower carried objects to even greater (or lesser) heights.
Roller Coaster l Roller coasters use a pulley to pull the train up the first hill. They also use inclined planes to help it reach the finish, wheels and axles for the car’s wheels to move, and screws to hold the trains together.
Bowflex l l The Bowflex uses many different simple machines, such as pulleys, a lever, screws, inclined planes, and wheels and axles. Pulleys can be visibly seen to add resistance for workouts, a lever can adjust parts, screws keep the machine together, wheels and axles allow for additional movement, and inclined planes are used in making the seat.
Bibliography l l l l http: //library. thinkquest. org/C 004451 F/nfpulley. htm http: //www. made-in-china. com/showroom/zygj 1986/productdetailtqbmuj. SCh. QIp/China-Crane-Pulley. html http: //www. schoolsliaison. org. uk/astonhall/candles/spits/pulley 1. htm http: //etc. usf. edu/clipart/25700/25757/fixed_pulley_25757. htm http: //www. school-for-champions. com/science/machines. htm This website gave me a simple definition of what a pulley was. http: //en. wikipedia. org/wiki/Pulley A great source for specific informaqtion, wikipedia gave me a ton of information that I needed to know throughout my slideshow. http: //www. technologystudent. com/gears 1/pulley 7. htm This website was extremely useful for teaching me how to find a pulley’s mechanical advantage. It offered diagrams and drawings in addition to this information.
Lever A Simple Machine By: Nicolas Joel Sholly The best
Lever (explanation) n A lever is a rigid object that when used with the right pivot point it multiplies the mechanical force to another object.
Mechanical Adv. n n To find the mechanical advantage you take the length of the arm giving effort divided by the arm giving resistance. MA= Effort Arm / Resistance Arm
Force n The torque on an object about some pivot point is due to the action of a force on the object. The lever trades force for distance by pulling or pushing to a section of the bar.
Complex Machines n A stapler is an example of a complex machine. The top arm is a lever and the staple is a wedge.
Wheel Barrel n A wheel barrel is a complex machine. It has a lever (handle bars), wheel and axel (wheel), and inclined plane (bucket).
Can opener n A can opener has four different simple machines. It has a lever (handles), wedge (blade), gear (turns can), wheel and axel (handle that is turned).
Bibliography n n n Edheads. org Wikipedia. org Enchantedlearning. com Vectorpark. com Library. thinkquest. org
The Screw Terry Mack Jr.
Screws-How? Screws can be used to apply force on objects, like vises, clamps and monkey wrenches. A screw could actually be described as an incline plane wrapped around an axis. Effort force is applied to the larger circumference of a screw, like someone turning a wood screw with a screwdriver. The force is transmitted down the spiral to the tip. The tip of the screw moves into the wood, and this is the resistance force.
Mechanical Advantage The ratio of the threads determines the mechanical advantage. The pitch is the distance between the threads. Suppose you have a screw with 12 threads per inch being turned by a screwdriver with a handle with a diameter of 1 inch. The pitch is. 083. Then you must find the circumference of the screwdriver handle. So, circumference = 3. 14 x diameter = 3. 14 x 1 = 3. 14 then, mechanical advantage = circumference/pitch mechanical advantage = 3. 14/. 083 mechanical advantage = 37. 83
Simple machines Incline
Incline n n An incline is a flat surface where the endpoints are at different levels. By moving an object up an inclined plane you need less force than pushing it up a vertical surface, but you have to go a longer distance.
Mechanical Advantage n The mechanical advantage of an incline is that the ratio of the length of the sloped surface to the height it spans. n You can find the mechanical advantage by dividing slope over height. ma=s/h
Changing of the force n n Inclines split the force into two smaller forces, one perpendicular and one parallel to the plane. Only the parallel force needs to be counteracted.
Example n n n For the picture below, assume that the length of the slope, or s, equals 15 feet. The height, or h, is 3 feet. Mechanical advantage=s/h =15/3 =5
Compound machine #1 n n Wheelbarrow Is made up of wheel & axle, lever and incline
Compound Machine #2 n n Rollercoaster Is made up of wheel & axle, pulley, and inclined plane
Compound Machine #3 n n Bench press It contains a wheel &axle and an incline slope
Annotated Bibliography n n n http: //en. wikipedia. org/wiki/Inclined_plane http: //www. uark. edu/depts/aeedhp/agscience/simp mach. htm http: //www. physicsforums. com/showthread. php? t=1 33529 http: //www. tooter 4 kids. com/Simple_Machines/inclin ed_plane. htm http: //reference. howstuffworks. com/inclined-planeencyclopedia. htm