Chapter 12 Work, Power, & Machines

I. What is work? A.Work – when force causes a change in an objects position. 1.Change must be in the direction force is applied.

Does this guy do work? Yes b/c the car changed position

II. Measuring Work A.The unit for work is the Joule (J). A Joule is equal to lifting an apple 1 meter (about 3 feet off the ground. An apple weighs about 4 ounces Work = Force x Distance Joules (J) = Newtons (N) x Meters (m)

Problem: An apple weighing 1 Newton falls a distance of 1 meter. How much work is done by the force of gravity? GIVEN: F = 1 N d = 1 m W = ? WORK: W = F x d W = (1 N)(1 m) W = 1 J F W d

Problem: While rowing in a race, John uses his arms to exert a force of 165 N per stroke while pulling the oar 0.8 m. How much work does he do in one stroke? GIVEN: F = 165 N d = 0.8 m W = ? WORK: W = F x d W = (165 N)(0.8 m) W = 132 J F W d

Assignment: Make your paper look like this: Work, Power, & Machines ABCDEFGHZABCDEFGHZ