Ch6+KloorfainN

Chapter 6

1/30 Lesson 2 A

All the types of forces could be categorized as contact forces or as action-at-a-distance forces. Whether a force was categorized as an action-at-a-distance force was dependent upon whether or not that type of force could exist even when the objects were not physically touching. The force of gravity, electrical forces, and magnetic forces were examples of forces that could exist between two objects even when they are not physically touching. Forces can be categorized as internal forces or external forces. E **xternal forces** include the applied force, normal force, tension force, friction force, and air resistance force. The **internal forces** include the gravity forces, magnetic force, electrical force, and spring force.

The importance of categorizing a force as being either internal or external is related to the ability of that type of force to change an object's total mechanical energy when it does work upon an object. When net work is done upon an object by an external force, the __ [|total mechanical energy (KE + PE)] __ of that object is changed. If the work is //positive work//, then the object will gain energy. If the work is //negative work//, then the object will lose energy. The gain or loss in energy can be in the form of __ [|potential energy] __, __ [|kinetic energy] __, or both. the work that is done will be __equal__ to the change in mechanical energy of the object. __ [|This principle will be discussed in great detail later in this lesson] __. Because external forces are capable of changing the total mechanical energy of an object, they are sometimes referred to as **nonconservative forces**. When the only type of force doing net work upon an object is an internal force, the __ [|total mechanical energy (KE + PE)] __ of that object remains constant. The object's energy changes form. For example, as an object is "forced" from a high elevation to a lower elevation by gravity, some of the potential energy of that object is transformed into kinetic energy. Yet, the sum of the kinetic and potential energies remains constant. This is referred to as energy conservation. 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. Because internal forces are capable of changing the form of energy without changing the total amount of mechanical energy, they are sometimes referred to as **conservative forces**.
 * < **Internal Forces** ||< **External Forces** ||
 * < **Fgrav****Fspring** ||< **Fapp****Ffrict****Fair****Ftens****Fnorm** ||

In the following descriptions, the only forces doing work upon the objects are internal forces - gravitational and spring forces. Energy is transformed from KE to PE (or vice versa) while the total amount of mechanical energy is conserved. Read each description and indicate whether energy is transformed from KE to PE or from PE to KE. When work is done by external forces (nonconservative forces), the total mechanical energy of the object is altered.

I got the first 5 right and then the next set I got 1/6 wrong!

It costs my parents approximately $148.65 a month for just some of the things I use with electricity. I think that my consumption will be maybe closer to $200. Most of the appliances listed are the major appliances I use but I use some others as well. Daily I use each item a different amount sometimes longer and shorter. The way I use electronics is expensive like per year that is over a $1000. I am going to start to unplug things when I am not using them to conserve energy.