Question

A tank is filled with water of density 1 gcm3 and oil of density 0.9 gcm3. The height of water layer is 100 cm and that of oil layer is 400 cm. If g=980 cms2, then the velocity of efflux from an opening in the bottom of the tank will be-

• A. (A) (952.53)cms
• B. (B) (940.23)cms
• C. (C) (949.53)cms
• D. (D) (939.54)cms

Answer 1

Answer: (C)

(C) (949.53)cms

Answer 2

Explanation:
Let d(w) and d(o) be densities of water and oil resp, then the pressure at the bottom of the tank will be=h(w)×d(w)×g+h(o)×d(o)×gLet this pressure be equivalent to pressure due to water of height hh×d(w)×g=h(w)×d(w)×g+h(o)×d(o)×gh=h(w)+[h(o)×d(0)d(w)]h=100+[400(0.9)1]h=100+360=460 cmAccording to Toricelli's theoremv=2ghv=2×980×460v=920×980v=901600Velocity of efflux =949.53 cmsHence, the correct option is (C).