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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumMulti-step

JEE Main 18 March 2021, Shift 2, Physics Q28

Question 28 of 90 in this shift, Physics question 28 of 30, Section B.

Consider a water tank as shown in the figure. It’s cross-sectional area is 0.4 m2^2. The tank has an opening B near the bottom whose cross-section area is 1 cm2^2. A load of 24 kg is applied on the water at the top when the height of the water level is 40 cm above the bottom, the velocity of water coming out the opening B is vv ms−1^{-1}. The value of vv, to the nearest integer, is _________. [Take value of g to be 10 ms−2^{-2}]

The figure, in words

A rectangular tank; a thick horizontal plate (piston) at the top, labelled A at its right end, with a hatched block on it labelled 24 kg; an opening B with a small fitting near the bottom of the right wall, with dotted lines showing water coming out.

Official answer

3

NTA final key.

Chapter
Mechanical Properties of Fluids
Topic
Fluid Dynamics
Idea tested
Torricelli's Law of Efflux

Same idea in other shifts

Asked 3× in all
  1. 28 Jul 2022, Shift 2 · Q7Consider a cylindrical tank of radius 1m is filled with water. The top surface of water is at 15 m from the bottom of the cylinder. There…MediumSingle correctHas a figure
  2. 27 Jun 2022, Shift 1 · Q59The area of cross-section of a large tank is 0.5 m20.5\ \mathrm{m^2}. It has a narrow opening near the bottom having area of cross-section…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.