- #1

baddin

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a) What air-pressure force will support a 1300kg car level with the compressed air piston?

b) How much must the air-pressure-force be increased to lift the car by 2m.

2. Homework Equations :

p = p + ρ*g*h

ρ=900kg/m^2

3. The Attempt at a Solution

I did a) by doing p + ρ*g*0 + F1/A1 = p + ρ*g*0 + F2/A2

Then used F1 = F2 * (A1/A2) to find that F1 is 730N, which is correct according to the solutions.

Then I attempted b) and used a similar approach.

I tried:

p + F1/A1 + ρ*g*(0) = p + ρ*g*h + F2/A2*

So I rearranged to get F1 = A1*ρ*h*g + (F2)*(A1/A2)

Finding A1, A2, and F2 easily, and using h =2m and ρ=900kg/m^3 and g = 9.8m/s^2, I keep getting F1 = 784N. So the increase in force should be 784N - 730N = 54N, but my book tells me the answer is 920N.