Following is a list of approximate conversion factors, useful for back-of-the-envelope estimates. None of them is exact,

Question:

Following is a list of approximate conversion factors, useful for “back-of-the-envelope” estimates. None of them is exact, but most are accurate to within about ±10%. Use Table A.1 (App. A) to establish the exact conversions.
∙ 1(atm) ≈ 1 bar
∙ 1(Btu) ≈ 1 kJ
∙ 1(hp) ≈ 0.75 kW
∙ 1(inch) ≈ 2.5 cm
∙ 1(lb_m) ≈ 0.5 kg
∙ 1(mile) ≈ 1.6 km
∙ 1(quart) ≈ 1 liter
∙ 1(yard) ≈ 1 m

Add your own items to the list. The idea is to keep the conversion factors simple and easy to remember.

Table A.1: Conversion Factors