An autonomous research probe descends into a liquid methane ocean on Saturn's moon Titan. The density of liquid methane is ρ=450 kg m−3\rho = 450\text{ kg m}^{-3}ρ=450 kg m−3 and the surface gravitational field strength of Titan is g=1.35 m s−2g = 1.35\text{ m s}^{-2}g=1.35 m s−2. The atmospheric pressure at the surface is p0=150 kPap_0 = 150\text{ kPa}p0=150 kPa.
The probe plots a graph of the total pressure PPP (measured in kPa\text{kPa}kPa) on the vertical axis against the depth ddd (measured in m\text{m}m) on the horizontal axis.
Which of the following equations represents this relationship?
P=0.61d+150P = 0.61 d + 150P=0.61d+150
P=610d+150P = 610 d + 150P=610d+150
P=0.61dP = 0.61 dP=0.61d
P=150d+0.61P = 150 d + 0.61P=150d+0.61