Question

how do you calculate root-mean-square (r.m.s) speed??

Answer 1

http://en.wikipedia.org/wiki/Root-mean-square_speed

this is if u meant gases

Answer 2

\[Vrms = \sqrt{3RT/M}\]

Answer 3

actually, in my question, i am supposed to find the root mean square speed of helium atoms.....i was given the formula
\[pV=\frac{ 1 }{ 3 }Nm <c ^{2}> \]

Answer 4

i was given the
pressure(p) = 6.1 x 10^5 Pa
Volume (V)= 2.1 x 10^4 cm^3
number of atoms (N)= 3.26 x 10^24

Answer 5

but i do not know why i am getting the answer wrong....

Answer 6

\[<c ^{2}>= mean -squared-speed\]

Answer 7

See:
\[pV = \frac{ 1 }{ 3 }Nm<c^{2}>\]
\[\sqrt{\frac{ 3pV }{ Nm }} = Vrms\]
We know that\[PV=NRT\] So:
\[\frac{ PV }{ N } = RT\] Then:
\[\sqrt{\frac{ 3RT }{ M }} = Vrms\]
So now u can use the values of p V and N as given to u in the question and follow the reverse of this derivation.

Answer 8

is the m the same as M

Answer 9

??

Answer 10

It is same if m means mass of 1 mole of the gas. So??????

Answer 11

so does that mean it would be 4 for the helium atom???

Answer 12

Yup

Answer 13

oh......i found my mistake......
thanks for the explanation!!

Answer 14

thnx for the medal

Answer 15

yw:)