Work and Machines: Work Chapter 5, Section 1 Notes Work and Machines: Work

Work is done when a force causes something to move. Work – transfer of energy that occurs when a force makes an object move. 1. For work to occur, an object must move. 2. The motion of the object must be in the same direction as the applied force on the object.

Work and energy are related, since energy is always transferred from the object doing the work to the object on which the work is done. Work is done on an object only when a force is being applied to the object and the object moves. For example, once a ball leaves your hand, work is no longer being done.

Calculating work – work equals force (in newtons) times distance Calculating work – work equals force (in newtons) times distance. W = Fd Practice Problems on page 128: 1. 2. 3. 4.

Power – amount of work done in a certain amount of time; rate at which work is done in one second. 1. Calculating power – power equals work divided by time. P = W/t 2. Power is measured in watts (W)

Practice Problems on page 130: 1. 2. 3. 4.

Since work and energy are related, power also can be calculated…power equals energy divided by time. P = E/t.