- #1
ZGMF - X20A
- 8
- 0
I just want to know in what conditions does mgh = 1/2mv^2 when a guy goes down a slope and in what conditions does mgh =/= 1/2mv^2. Thanks in advance.
Understanding Mgh = 1/2mv^2: Conditions for Equal and Unequal Energy on Slopes
- Thread starter ZGMF - X20A
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Homework Help Overview
The discussion revolves around the conditions under which the equation mgh = 1/2mv^2 holds true for an object moving down a slope, as well as the scenarios where this equation does not apply. The subject area includes concepts of energy conservation, potential energy (PE), and kinetic energy (KE).
Discussion Character
- Exploratory, Conceptual clarification, Assumption checking
Approaches and Questions Raised
- Participants explore the relationship between potential energy and kinetic energy, questioning the conditions under which energy conservation applies. Some suggest using the conservation of energy principle, while others consider the impact of initial velocity and non-conservative forces like friction.
Discussion Status
The discussion is active, with participants providing insights into energy conservation and the effects of friction. There is an exploration of different interpretations regarding the equations and conditions, but no explicit consensus has been reached.
Contextual Notes
Participants are considering various factors such as initial velocity and the presence of friction, which may affect the application of the energy equations. The discussion acknowledges the importance of distinguishing between conservative and non-conservative forces.
- #2
semc
- 364
- 5
according to COE, (initial)PE + KE = PE + KE(final) so i think that its better to use this instead of your equation.For example,if the object were to be released with some initial velocity,the KE(initial) would not be 0 so total initial energy is mgh+1/2mv^2 instead of mgh.Btw,it is more precise to write change of PE = -change of KE as this shows that energy is conserved.
- #3
HallsofIvy
Science Advisor
Homework Helper
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And energy is conserved as long as the are no "non-conservative" forces- i.e. as long as there is no friction.
- #4
ZGMF - X20A
- 8
- 0
So when there is no friction P.E = K.E?
- #5
Tomsk
- 227
- 0
Yes, decrease in PE= increase in KE and vice versa. If there's friction, decrease in PE= increase in KE + energy 'lost' to surroundings, so increase in KE<decrease in PE.
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