1) It should be absolutely clear to you that energy conservation can be expressed as thework put into a system = change in energy of that system less what ever leaks out. The energy change of the system includeds its KE, its PE, and its thermal ( microscopic) energy.
In other words: Work in = Delta KE + delta PE +losses (including all forms of "microscopic" energy such as heat, noise, light. Some of the heat stays in the system and some is lost. The heat that stays in yields a rise in system microscopic nery i.e. delta U).
In the stair lab, we are ignoring losses to heat etc. Thus Win = Mgdelta h + Mv sqrd/2.Win does not equal KE. While KE does equal Fnet dot distance most of the time, this fact is useless here since you cannot calculate the net force very well.
Note KEi = 0 so delta KE = the KE you calculated.
The proportion of average power used to create the KE is (KE/delta t)/(total delata E/delta t) or just the KE dic=vided by the total work done since the delta ts cancel.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment