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2002 Past Paper Q22ci - HSN forum

# 2002 Past Paper Q22ci

### #1jambo david

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Posted 16 January 2006 - 04:52 PM

Calculate the force exerted by the nitrogen on the piston when the reading on the pressure gauge is 1.75*10^5Pa.

I tried using p=f/a but there is no area given that i can see.

### #2Nathan

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Posted 16 January 2006 - 05:52 PM

22.a. P1 = 109kPa
T1 = (15+273)K = 288K

P2 = ?
T2 = (45+273)K = 318K

P1/T1 = P2/T2
P2 = P1T2/T1
P2 = 109x318/288
P2 = 120.35kPa

b.   As the temperature increases the nitrogen gas molecules gain
kinetic energy. With increased kinetic energy the atoms are moving
faster and collide with the container walls more frequently
and forcefully. The pressure(force/area) therefore increases.

c.i. P = 1.75x105Pa
A = 4.0x10-6m2

F = PA
F = 1.75x105x4.0x10-6
F = 0.7N

c.ii. Read from the graph the length of the spring when the force
is 0.7N.

Length = 35mm

d. The assumption in the original set up is that the temperature
of the water is the same as the temperature of the gas inside
a more direct and accurate reading of the gas temperature.

Area of piston is given in Q as 4.0 x 10-6m2

Edited by nathanm, 16 January 2006 - 06:06 PM.

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