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Mechanical Advantage Of Machines

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Mechanical Advantage Of Machines

  1. 1. Mechanical Advantage of Machines Karen M. Abbago General Science
  2. 2. Mechanical Advantage <ul><li>The number of times a simple machine will multiply a force </li></ul><ul><li>There are two types of mechanical advantages: </li></ul><ul><li>Theoretical mechanical advantage </li></ul><ul><li>Actual Mechanical Advantage </li></ul>
  3. 3. Two types of M.A. <ul><li>When the machine is not yet used, we can compute for the mechanical advantage. </li></ul><ul><li>We have to take into consideration the distance the effort will move and the distance the load will move . </li></ul><ul><li>The number of times the machine has actually helped in doing work </li></ul><ul><li>We have to know the amount of force put into the machine ( effort ) and the amount of force the machine produces ( load) </li></ul>TMA AMA
  4. 4. Effort <ul><li>The force applied on </li></ul><ul><li>a machine. </li></ul>
  5. 5. Load <ul><li>The force produced or resistance of a machine </li></ul>
  6. 6. Equations = force produced = load or resistance force applied effort = distance effort moves (d E ) distance load moves (d L ) TMA
  7. 7. Efficiency of machines <ul><li>No matter how much work we put into the machine( input work) the work done by the machine is (output work) is always less than what you put in. </li></ul><ul><li>It is because friction between the machine parts converts some of the input work into useless heat. </li></ul><ul><li>We depend on machines so we have to better understand how they work. </li></ul>
  8. 8. <ul><li>% Efficiency= work output x 100% </li></ul><ul><ul><ul><ul><ul><li>work input </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>% Efficiency= AMA/TMA </li></ul></ul></ul></ul></ul>Efficiency Equation
  9. 9. Sample problems on M. A. <ul><li>A machine has a mechanical advantage of 5. If a balikbayan box weighing 1000N is to be lifted onto a truck, how much effort is needed? </li></ul><ul><li>Given: AMA= 5 R= 1000N </li></ul><ul><li>Required: Effort or E=? </li></ul><ul><li>Formula: AMA= R </li></ul><ul><li>E </li></ul><ul><li>Solution: E= 1000N/ 5 </li></ul><ul><li> E= 200 N </li></ul>E= R/AMA
  10. 10. Sample problems on M. A. <ul><li>A machine with a TMA of 5 and an AMA of 4 is used to raise a 10.0 kg balikbayan box by 5.00 m. What is the work input to the machine? </li></ul><ul><li>Given: TMA= 5 AMA= 4 m= 10.0 kg </li></ul><ul><li> h= 5.0 m </li></ul><ul><li>Solution: W in = mgh </li></ul><ul><li> = (10.0kg)( 9.8m/s 2 ) (5m) </li></ul><ul><li> = 490 J </li></ul><ul><li>Efficiency= AMA/ TMA x 100% </li></ul><ul><li> = 4/5 x 100% </li></ul><ul><li> = 80% </li></ul>
  11. 11. <ul><li>Efficiency= work output/work input </li></ul><ul><li> 0.80 = 490 J/ work input </li></ul><ul><li>0.80 (work input )= 490J </li></ul><ul><li>0.80 .80 </li></ul><ul><li>Work input= 613 J </li></ul>
  12. 12. Make it Easy by Trial <ul><li>A machine has a TMA of 6 and an AMA of 4. What is the efficiency of the machine? </li></ul><ul><li>A machine is 48% efficient and has an M.A. of 3.0 Find its TMA. </li></ul><ul><li>A machine that is 75% efficient lifts a wooden crate of 750.0N to a height of 3m.The machine’s TMA is 2. </li></ul><ul><li>Find: </li></ul><ul><li>a. the applied force or effort needed to raise the crate. </li></ul><ul><li>b. the work input </li></ul>
  13. 13. REMEMBER! <ul><li>It always takes a certain amount of work for all machines to overcome friction. This is why all machines are less than 100% efficient. </li></ul>
  14. 14. What should we do to minimize the effects of friction? <ul><li>Rollers, lubricants or oils, polished surfaces and streamed lined vehicles can reduced the amount of friction. </li></ul>

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