Physics quiz question: elevation of Lake Baikal

Physics 205A Quiz 5, fall semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problems 9.27, 9.31

In August 2009, aboard the mini-submarine Mir-1, Russian Prime Minister Vladmir Putin dived 1,400 m below the surface of Lake Baikal in Siberia[*], the world's deepest lake. The pressure at the surface of the lake is 95.9 kPa. The surface of Lake Baikal is located at an elevation __________ sea level. (P_atm = 101.3 kPa.)
(A) above.
(B) at.
(C) below.
(D) (Not enough information is given.)

[*] Source: Stuart Williams, "Putin dives to bottom of world's deepest lake," Agence France-Presse, August 1, 2009.

Correct answer: (A)

The pressure of the atmosphere at sea level is given as P_atm = 101.3 kPa, such that for the (atmospheric) pressure at the surface of Lake Baikal to be less than the pressure at sea level, the surface of Lake Baikal must be higher than sea level, as given from:

0 = ∆P + ρ_air*g*∆y.

Sections 70854, 70855
Exam code: quiz05t0rQ
(A) : 32 students
(B) : 3 students
(C) : 14 students
(D) : 2 students

Success level: 63%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.30