Assume this piston has a maximum pressure rating of 2.5 pounds-force per square inch [psi]. The force applied to the cylindrical piston is 100 newtons [N]. What is the diameter of the piston, in units of inches [in]

Explanation:

Always write what you know first about the problem

The surface of the piston that has the force applied is a circle

The area of a circle is pi x r^2

Pressure is Force / Area

Write this out

P = F / (pi x r^2)

solve for r

sqrt( F / (P x Pi)) = r

But dont forget that d = 2 x r

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s