1. CHAPTER 5 Work and Machines

2. DEFINITIONS Effort Force - (F e ) the force put into a machine Resistance Force - (F R ) the force moved by a machine Weight is a force. F = ma (mass in kg) (acceleration of gravity) Energy - the ability to do work Measured in Joules Mechanical Advantage - the number of times a machine multiplies the force or work put into a machine

3. Formulas Work = Force x distance W = F x d 1 N  m = 1 Joule Power = Work / timeP = W / t 1 Watt = 1 J/s = 0.239 cal/sec Efficiency = (W OUT ) / (W IN ) x 100%

4. Levers MA = (Length of effort arm) / (Length of Resistance arm) MA = L e / L R

5. Inclined Plane MA = (Length of slope) / (height of slope) MA= l / h

6. Wheel and Axle MA = (radius of wheel) / (radius of axle) MA = r W / r a

7. Gears A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque Torque - a rotating force

8. Pulleys Fixed Pulley MA = 1 Moveable Pulley MA = L E / L R Block & Tackle MA = Number of ropes in the system

9. Wedges and Screws

10. USE YOUR NOTES TO STUDY FOR THE CH. 5 TEST WEDNSEDAY FEB 9 th TODAY’S ASSIGNMENT IS DUE MONDAY FEBRUARY 7 th