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Thermal Physics

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Joined:	13 Aug 2007
Post:	25

23 Jan 2008 11:21:20 IST

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446

somebody solve it....

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PLS DONT NEGLECT IT THINKING IT TO BE A LONG QUESTION....

1)an ideal gas is trapped btn a mercury column and closed end of a narrow vertical tube of uniform base containing the column. the upper end of the tube is open to the atmosphere. the atmospheric pressure equals 76 cm of mercury.the length of the mercury column and the trapped air column are 20 cm and 43cm respectively. what will be the length of the air column when the tube is tilted slowly in a vertical plane through an angle of 60 degrees?

assume the temperature to remain constant?

ANS:48cm.

2)a vertical cylinder of height 100cm contains air at a constant temperature. the top is closed by a frictionless light piston. the atmospheric pressure equals to 75 cm of mercury. mercury is slowly poured over the piston. find the max ht of the mercury column that can b put on the piston?

ANS:25cm

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Comments (1)

NITESH BASKARAN

Blazing goIITian

Joined: 29 Sep 2007

Posts: 487

23 Jan 2008 13:30:51 IST

Like 2 people liked this

2.
since temperature remains constant
PV=constant
initial pressure = 75 cm Hg
initial volume = 100A
A-area
let the length of cylinder containing gas be h
then final volume = Ah
final pressure = ( 75 + 100-h)
where 100-h is the height occupied by mercury
75 x 100 = h(175-h)
solve the quadratic
the two solutions are h= 100 and h = 75
h= 100 is not possible
therefore h=75
height of mercury = 100-75 = 25cm

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