The pressure of a gas in a well-sealed vertical frictionless piston-cylinder device is to be increased by adding a mass of 25 kg on the piston. If the diameter of the cylinder is 14 cm, the increase in the pressure of the gas is
A)15.9 kPa
B) 0.25 kPa
C)0.56 kPa
D)1.8 kPa
E) 38.7 kPa

Question

Quizplus · Accepted Answer

Solved by EES Software. Solutions can be verified by copying-and-pasting the following lines on a blank EES screen. 
m=25 "kg"
g=9.81 "m/s2"
W=m*g/1000 "kN"
D=0.14 "m"
A=pi*D^2/4 "m^2"
P=W/A "kPa"
"Some Wrong Solutions with Common Mistakes:"
 W1=W "Ignoring piston area"
 W2=W/D "using D instead of A"
W3=W/(pi*D) "using perimeter instead of area"

The Pressure of a Gas in a Well-Sealed Vertical Frictionless