Chapter 12 Work and Energy Section 1 Work, Power, and Machines p. 378

Understand simple machines Objectives Understand simple machines Evaluate the relationship between energy, work, and power

I. Work- transfer of energy to a body by the application of a force that causes the body to move in the direction of the force A. W=F x d – for work to take place there must be movement B. Measured in Joules 1 J = 1 N x m = 1 kg x m2/s2 II. Power – the rate at which work is done or energy transformed A. Power= work/time P= w/t B. Measured in watts W=J/s

III. Machines and Mechanical Advantage A. Machines multiply and redirect force B. Mechanical Advantage- how much a machine multiplies force or increases distance 1. Ratio between output force and input force 2. Ratio between input distance and output distance (if friction is ignored- ideal mechanical advantage) 3. MA = output force/input force = input distance/output distance

Homework Stairs worksheet Read 12.1 and 12.2