Convert 45 psi of oil with a specific gravity of 0.9 to ft of head of oil.

To convert pressure in psi to feet of head, you can use the formula that incorporates specific gravity. The formula for converting psi to feet of head is:

[ \text{Head (ft)} = \frac{\text{Pressure (psi)} \times 2.31}{\text{Specific Gravity}} ]

In this case, the pressure is 45 psi and the specific gravity of the oil is 0.9. Plugging in these values gives:

[ \text{Head (ft)} = \frac{45 \times 2.31}{0.9} ]

Calculating this step-by-step:

1. Multiply 45 psi by 2.31, which equals 103.95.

2. Next, divide 103.95 by the specific gravity of 0.9:

[ 103.95 \div 0.9 = 115.5 ]

Thus, the head of oil is approximately 115.5 feet, which corresponds to the correct answer. This method takes into account the pressure exerted by the fluid and its density in relation to water, which is essential for conversions in hydraulic applications where the relative density of fluids is a factor.