Ch. 5 Work, Energy, and Power

Bellwork 3/6/2018 Which student is doing work on the chair?

Work In physics, work has a very specific meaning. In physics, work represents a measurable change in a system, caused by a force.

Formula for Work W = F x d (cos θ) Whenever θ = 90°…….. Then work = 0 Force is measured in Newtons (N) Distance is measured in meters (m) N x m = Joules

Requirements for work: An object has to: 1) experience a force AND………………………………. 2) Move a distance ( measured in meters) in the same direction as the applied force.

Work If you push a box with a force of one newton for a distance of one meter, you have done exactly one joule of work.

A. Positive Work is done B. Negative Work is done C. No Work is done

Checkpoint You have 5 minutes to research one example of positive, negative, and zero work being done.

Sample Problem A 20.0 N tension force is applied to a suitcase to raise it 3.0 m above a platform by a conveyor belt. How much work is done on the suitcase? Draw a free-body diagram to represent the scenario.

Only use the force acting on the suitcase 3.0 m FTension = 20.0 N FGravity Only use the force acting on the suitcase W = F x d W = 20.0 N x 3.0 m W = 6.0 x 101J

Classwork Page 163 #’a 1-6 (except #4)