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Mechanical Advantage vs. Mechanical Efficiency. Simple Machines. Machines and Work. We said that machines make work easier b/c they change the size or the direction of the force (input). Force is measured in Newtons (N). Mechanical advantage vs Mechanical Efficiency.
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Mechanical Advantage vs. Mechanical Efficiency Simple Machines
Machines and Work • We said that machines make work easier b/c they change the size or the direction of the force (input). • Force is measured in Newtons (N)
Mechanical advantage vs Mechanical Efficiency • Mechanical Advantage (MA) - tells how many times a machine multiplies force • Formula Mechanical Advantage = output force Input force
Mechanical Advantage (continued) If your result is : • greater than 1 = the output force is greater than the input force (this is what you want b/c you don’t want to put in more force than you get out) • less than one = it requires more input force from you and does not have a mechanical advantage
Practice Problems for Mechanical Advantage (MA) You have to push a 500N weight up a ramp and have to push with a force of 50N. What is the Mechanical Advantage? • MA = output force so = Input force • The output force is ________ times greater than the input force
Practice Problems for Mechanical Advantage (MA) • Grace uses a cart to lift canned foods. She uses an input force of 40 N to the cart and the cart applies an output force of 320 N . What is the Mechanical Advantage of the cart? • MA = output force so ____________ = Input force • The output force is ________ times greater than the input force
Practice Problems for Mechanical Advantage (MA) • If the Mechanical Advantage a Machine is 5, what does this mean? • This means that the output force of the machine is 5 times greater than the input force
Mechanical Efficiency • is shown as a percent (%) that compares work output to work input. • Work is measured in Joules • Mechanical Efficiency • = work output X 100 Work input • This will give you a percentage
Mechanical Efficiency (continued) • **A machine cannot be 100% efficient b/c Machines have moving parts which create FRICTION which causes energy input to be lost as heat..
Mechanical Efficiency (continued) QUESTION: • What is the mechanical efficiency of a machine whose work input is 100J and work output is 30 Joules ??? • ME = work ouput X 100 Work input • 30 X 100 = 30 percent 100
How do I remember MA and ME • ** A WAY TO REMEMBER THE DIFFERENCE BETWEEN MECHANICAL ADVANTAGE AND MECHANICAL EFFICIENCY IS • MA FORCES ME TO DO WORK • (MA INVOLVES FORCE, ME INVOLES WORK)