A circular piston exerts a pressure of 80 k Pa on a fluid, when the force applied to the piston is 0.2kN. What is the diameter of the piston ?

2 Answers
Mark C.
Oct 1, 2017

#P = F/A# rearranged for area, A. You then need to find the diameter from # A = pi r^2# remembering to double the radius to get diameter.

Explanation:

A = #F/P= 200/80000#

A = #0.0025 m^2#

r = #sqrt(A/pi)# = #sqrt(0.0025/pi#

r = 0.028 #m#

D = 2r = 0.056 m

Steve J.
Oct 1, 2017

The diameter is 0.056 m.

Explanation:

Pressure is force divided by area.
Therefore, by the manipulations of algebra, area = force/pressure.

So the area of the piston is given by
#"area" = (0.2 kN)/(80 k Pa) = (0.2*cancel(10^3) cancel(N))/(80*cancel(10^3) cancel(N)/m^2) = 0.0025 m^2#

To find diameter we first need to get the radius using the formula for the area of a circle.
area = #pi*r^2 to# from that, we can obtain
#r = sqrt("area"/pi) = sqrt((0.0025 m^2)/pi) = 0.028 m#

So the diameter is 0.056 m.

Or 5.6 cm if you prefer.

I hope this helps,
Steve

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