Need some help solving these tough Physics questions please....
Question 1
What is the Heat Capacity of a system consisting of a 0.475kg brass cup filled with 0.051kg of water?
Question 2
A container of nitrogen (N2)gas at 9.7oC contains 405 L at a pressure of 3.38 atm. If 27.4 kJ of heat are added to the container, what will be the new temperature?
I think you first determine the numberof moles.
2007-11-13 07:42:23 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Physics
1. Heat is proportional to mass, specific heat capacity an difference in temperature.
Q=mCp(T2-T1)
m - mass (kg)
Cp - specific heat
T- temperature (deg K)
Q=Q1+Q2
Assuming the temperature is the same
Q= (m1Cp1 + m1Cp2)T
Heat capacity will be th energy required to change the temperature from T1 to T2
2. Yes you are correct we must determine the mass of N2
PV=nRT
P-pressure
V-volume
n - number of mols
R - gas constant
T- temperature (deg K)
n= PN/(RT)
mass= m=(2 x 14.01 g/mol)n
m=28.02PN/(RT) (grams)
Q=mCp(T2-T1)
T2= Q/(mCp)+ T1 where Q=27.4 kJ
2007-11-13 07:52:23 · answer #1 · answered by Edward 7 · 1⤊ 0⤋
in question 2 you will need to find mols, n, using pv=nrt by solving for n......n= pv/rt. get r from this webpage.
http://en.wikipedia.org/wiki/Gas_constant
use the second r from the top in the table at the right because
you need r that can be stuck in the equation pv=nrt.
then find cv for nitrogen gas from this link
http://en.wikipedia.org/wiki/Heat_capacity#Heat_capacity
cv for n2 will be down about 25 boxes down in the table of cv values. be sure to use the one for gas which is at the far right.
now that you know mols and cv you can use the equation you got from your other yahoo answer. you gotta use cv instead of cp for a gas in a tank that will keep its same volume while heat is added. Q = 27400 joules. n=mols you calculated. cv=number you got from table. tinitial = 273+9.7. tnew is what you will calculate. Q=n(Cv)(tnew-tinit).
2007-11-13 08:18:43 · answer #2 · answered by Anonymous · 0⤊ 2⤋
K.E = 339 KeV = 339*10^3*1.6*10^-19 J We Know Energy = h(planck's constant) * frequency h=6.626*10^-34 Js Hence frequency(f) = (339*10^3*1.6*10^-19)/(6.626*10^-34) From this answer c = Lambda(wavenlength) * f where c = 3*10^8 m/s hence lambda = c/f
2016-04-03 23:10:49 · answer #3 · answered by Anonymous · 0⤊ 0⤋