what is mechanical advantage? the force you apply to a machine is called the effort force (input...

Download What is mechanical advantage? The force you apply to a machine is called the effort force (input force) The force that the machine applies is the resistance

Post on 27-Dec-2015

213 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Slide 1
  • What is mechanical advantage? The force you apply to a machine is called the effort force (input force) The force that the machine applies is the resistance force (output force) To open a can, you apply a force of 50 N to the can opener. The can opener applies a force of 775 N to the can. The machine multiplies your effort force so work becomes easier A machine lets you use a small force to overcome a large force The number of times a machine multiplies the effort force is called its mechanical advantage
  • Slide 2
  • How to calculate mechanical advantage: MA = resistance force effort force The resistance force is often equal to the weight of an object being moved EX: To crack a pecan, you apply a force of 50 N to the nutcracker. The nut cracker applies a force of 750 N to the pecan. What is the MA? MA = RF EF MA = 750N 50N MA = 15 (no units used) The higher the mechanical advantage, the easier work is!
  • Slide 3
  • Calculate Mechanical Advantage: You apply a force of 100 N to a pulley. The pulley applies a force of 800 N to lift a boulder. What is the mechanical advantage? MA RF EF X
  • Slide 4
  • How to determine MA of a lever Every lever has two parts, an effort arm and a resistance arm The effort arm is the distance from the effort force to the fulcrum The resistance arm is the distance from the resistance force to the fulcrum MA = effort arm length/ resistance arm length (input) (output)
  • Slide 5
  • Finding MA for a Fixed Pulley Fixed pulleys only change direction of the effort force, not the amount The effort force is equal to the resistance force As a result, the MA of a fixed pulley is always equal to 1 Ex: If the effort force = 20 N and the Resistance force = 20 N, what is the MA? MA = RF EF MA = 20N 20N MA = 1 A fixed pulleys MA always = 1
  • Slide 6
  • Finding MA for Moveable Pulleys and Pulley Systems You can find the MA of a moveable pulley by counting the number of ropes that lift the resistance A pulley system is made up of both fixed and moveable pulleys The pulleys are used together to increase the MA of the system The MA of a pulley system is equal to the number of supporting ropes MA = 2
  • Slide 7
  • The MA of a pulley system is equal to the number of supporting ropes Determine the MA of each pulley system: MA = 2 MA = 3 MA = 4
  • Slide 8
  • Finding MA of an inclined plane (ramp) You can find the mechanical advantage of an inclined plane by dividing its length by its height MA = length / height MA = 3 m / 1 m MA = 3 Length Height

Recommended

View more >