1. Energy and Work

2.  Formulas:  W = Fd ▪ Units of work are the joule (J)

3.  W = Fdcosθ ▪ Use this formula if the object moves horizontally and you are given an angle ▪ Calculator must be in degree mode! ▪ Plug in the angle for θ

5.  W = Fdsinθ ▪ Use this formula if the object moves vertically and you are given an angle ▪ Calculator must be in degree mode! ▪ Plug in the angle for θ

7.  KE = ½ mv 2  Looking at this formula, what accounts for most of the kinetic energy?

8.  ΔK = W  The _______ in kinetic energy equals work; and the amount of work done represents the _______________in kinetic energy.

9.  Example problem 1  A student lifts a box of books that weighs 185 N. The box is lifted 0.800 m. How much work did the student do?

10.  List all variables:  185 N is a _____________  0.800 m is a ___________  We’re solving for work… so W = ?

11.  F = 185 N  d = 0.800 m  W = ?

12.  Example problem 2  A 0.18 kg ball falls a distance of 2.5 m. How much work does the force of gravity do on the ball?

13.  m = 0.18 kg  d = 2.5 m  W = ? You need force and distance to find work, right? Do you have them?

14.  Use F = ma to solve for force, then use force and distance to find work