Simple Machines and Mechanical Advantage. SPS8E – IN 33 Physical Science Ms. Lockhart. What Are the Six Simple Machines?. Screw. Wedge. Inclined Plane. Pulley. Wheel and Axle. Lever. How Do Simple Machines Make Work Seem Easier?. Simple Machines just change The direction of the force
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Simple Machines and Mechanical Advantage SPS8E – IN 33 Physical Science Ms. Lockhart
What Are the Six Simple Machines? Screw Wedge Inclined Plane Pulley Wheel and Axle Lever
How Do Simple Machines Make Work Seem Easier? • Simple Machines just change • The direction of the force • The amount of force you exert • The distance that force has to travel
Work is Constant Machines make work SEEM easier but it is the same amount of WORK.
Although it takes less force for car A to get to the top of the ramp, all the cars do the same amount of work. A B C
Inclined Plane • Further distance, less effort.
Mechanical Advantage (MA) • MA = distance of ramp • height of ramp • = 15/3 = 5 • Work seems five times easier 15 m Din Dout 50 N 3 m Fin 10 N
Mechanical Advantage (MA) • MA = Output Force • Input Force • 50/10 = 5 • Work seems five times easier SAME ANSWER! Fout 15 m Din Dout 50 N 3 m Fin 10 N
MA-Wheel and Axle Small gears rotate faster than larger gears. Larger Gear Smaller Gear
How to Calculate the MA of a Wheel and Axle? • 2. The wheel of a small dirt bike has a radius of 30 cm. The axle has a radius of 20 cm. What is the mechanical advantage of the wheel and axle? • 5. The mechanical advantage of a steering wheel is 15. If the radius of the steering column (axle) is 5 cm, what is the radius of the steering wheel?
Essential Questions p. 23 (Answer questions 3 on page 22)
What is the MA of a Pulley? • MA • One Fixed pulley: • MA • Count # ropes supporting the pulley. Movable Pulley:
Choice • Students will have an opportunity to work on the mechanical advantage of simple machines by either: • Website – Find the MA of pulleys (slide 12) • Website – Test your knowledge of simple machines (slide 13) • Cooperative Groups – The manager will quiz you on identifying simple machines and mechanical advantage. (handouts)
Practice - Pulleys MA • http://www.dynamicscience.com.au/tester/solutions/hydraulicus/pulleys2.htm • Calculate the MA for each picture. Start with the first and then select ‘exercise’. When you get to the bottom, select ‘continue’. • First picture – 4 strings (MA 4) • Second picture – 4 strings (MA 4) • Third picture – 3 strings (MA 3) • Four picture – 4 strings (MA 4) • Fifth picture – 3 strings (MA 3) • Sixth picture – same • Seventh picture (wow!) – 6 strings (MA 6)
Activity – Label Simple Machines • Going further: Try this online activity! • http://www.teachengineering.org/collection/cub_/lessons/cub_simple/cub_simple_lesson01_worksheet.pdf • Answers • 5, 3, 6, 2, 1, 4 • Pulley (car has wheel and axle), Wheel and axle, Wheel and axle AND lever • Wedge, Lever, Screw • Incline plane, Incline plane, Wheel and axle • Lever, Lever, Pulley
The Lever • A bar with a fixed point (fulcrum).
Types of Levers MA = Input Arm Output Arm
First Class Lever EFR (1st Class) Fulcrum is in the middle area
First Class Lever - Examples Examples • Crowbars • Scissors • Pliers • Tin snips • Seesaws
Second ClassLever FRE (2nd Class) Fulcrum is at the end Your work is at the end (effort force)
Second Class Lever Examples • Nut crackers • Wheel barrows • Doors • Bottle openers
Third Class Lever FER (3rd Class) Fulcrum is on the end. Your work is in the middle area
Third Class Lever Examples • Tweezers • Arm hammers • Shovels
Practice - Choice • Cooperative Groups – secretaries will test your knowledge of simple machines, mechanical advantage and types of levers. • Study – read over your notes for p. 33. Write a summary of what you learned or what is most important and why. • EQ – complete the EQ for this topic (p. 22) – SPS8E #3 • Unpack the Standard – Unpack standard 8 (can be computer work) • Relearn – review the BrainPop videos on the topic.
BrainPop • Pulley - http://www.brainpop.com/technology/simplemachines/pulley/ • Levers - http://www.brainpop.com/technology/simplemachines/levers/ • Incline Plane – • http://www.brainpop.com/technology/simplemachines/inclinedplane/
Rube Goldberg Machines • Rube Goldberg machines are examples of complex machines. • All complex machines are made up of combinations of simple machines. • Rube Goldberg machines are usually a complicated combination of simple machines. • By studying the components of Rube Goldberg machines, we learn more about simple machines and energy transformations.
Rube Goldberg Machine Honda Commercial • http://www.teachertube.com/viewVideo.php?video_id=15955 Japanese Rube Goldberg • http://www.dailymotion.com/video/x14rj6_pitagora-suicchi-rube-goldberg-mach_fun