Register to reply

Mgh = 1/2mv^2

by ZGMF - X20A
Tags: 1 or 2mv2
Share this thread:
ZGMF - X20A
#1
Sep29-06, 07:42 AM
P: 8
I just wanna 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.
Phys.Org News Partner Science news on Phys.org
Experts defend operational earthquake forecasting, counter critiques
EU urged to convert TV frequencies to mobile broadband
Sierra Nevada freshwater runoff could drop 26 percent by 2100
semc
#2
Sep29-06, 08:08 AM
P: 331
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.
HallsofIvy
#3
Sep29-06, 08:33 AM
Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,568
And energy is conserved as long as the are no "non-conservative" forces- i.e. as long as there is no friction.

ZGMF - X20A
#4
Sep30-06, 02:51 AM
P: 8
Mgh = 1/2mv^2

O.o
So when there is no friction P.E = K.E?
Tomsk
#5
Sep30-06, 04:17 AM
P: 227
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.


Register to reply