Ch6_souflige

Chapter 6

Lesson 1 - Work, Energy, and Power
A. Work

After reading the material, answer the following questions: I already understood the meaning of the vectors and the meaning of theta. Theta is between force and displacement.
 * 1) What (specifically) did you read that you already understood well from our class discussion? Describe at least 2 items fully.

none.
 * 1) What (specifically) did you read that you were a little confused/unclear/shaky about from class, but the reading helped to clarify? Describe the misconception you were having as well as your new understanding.
 * 1) What (specifically) did you read that you still don’t understand? Please word these in the form of a question.

What is the significance of work and why does it need its own unit of measurement?

Work, measured in Joules (newtons*1 meter) is a measurement of the amount of displacement caused by a force being exerted on an object. The equation is W=F*d*cos(theta). There is no work being done if the object shows no displacement.
 * 1) What (specifically) did you read that was not gone over during class today?

A. Internal vs. External Forces
There are a variety of ways to categorize all the types of forces. Forces can be categorized based upon whether or not their presence is capable of changing an object's [|total mechanical energy]. Some can change the total mechanical energy in an object through doing work, and some can only transform energy. The two categories of forces are referred to as internal forces and external forces. E**xternal forces** include the applied force, normal force, tension force, friction force, and air resistance force. ** Internal forces ** include the gravity forces, magnetic force, electrical force, and spring force. External forces: If the work is //positive work// (force & displacement in same direction), then the object will gain energy. If the work is //negative work// (force & displacement in opposite direction), then the object will lose energy. The gain or loss in energy can be in the form of [|potential energy], [|kinetic energy] , or both. Work = change in mechanical energy (** nonconservative forces **). Internal Forces: When the only forces doing work are internal forces, energy changes forms - from kinetic to potential (or vice versa); yet the total amount of mechanical is conserved (** conservative forces **).