Home Physics Fluid Mechanics Mix An open beaker is lowered into a vessel cont…
Physics Fluid Mechanics Mix Subjective Type
Published on: September 12, 2026

An open beaker is lowered into a vessel containing water, once bottom upwards, and once bottom downwards (Fig.), both times to the same depth. In which of the two cases will the work which must be expended on dipping the beaker into the water be greater? (The water does not spill out of the vessel, nor does it flow over into the beaker when dipped in bottom downwards.)

Share this question

For Instagram sharing, use “Apps” on mobile or copy the link.

Text Solution

Verified by Experts
The correct answer is:
B
Step 1: Understand the setup
We have an open beaker being dipped into water in two orientations: one with the bottom up (beaker 1) and another with the bottom down (beaker 2). The depth to which the beaker is submerged is the same in both scenarios.

Step 2: Analyze the scenarios
When the beaker is positioned with the bottom up, the water enters the beaker and starts to exert a buoyant force inside it. In this case, as the beaker is depressed, the air inside cannot escape initially, requiring additional work to push against the buoyancy caused by the air pressure and eventually leading to water displacement.
In contrast, when the beaker is positioned with the bottom down, the air inside can escape more easily when the beaker is pressed into the water, easing the pressure difference.

Step 3: Calculate work done
The work done to dip the beaker depends on the pressure and the buoyant forces acting on it. The upward buoyant force when the beaker is upside down (beaker 2) is less compared to what the beaker experiences when it's right side up (beaker 1) because less air volume needs to be displaced for the same depth of water.

Step 4: Conclusion
Since the beaker oriented with the bottom up (beaker 1) has to overcome a greater buoyant force due to both water and trapped air, it will require more work to submerge it compared to the bottom down configuration (beaker 2). Thus, more work must be exerted in the case of the beaker oriented bottom up.

Therefore, the correct answer is B.

Prepare Smarter with CGP Edu

Get practice questions, solutions, and test series in one place.

Write a Review

Share your experience with this question and solution.

Commentary

Send your comment, doubt, correction, or feedback to admin.

Student Reviews

What students say about this solution

No reviews yet. Be the first to write a review.

Similar Questions

Explore conceptually related problems

CG
CGP Question Assistant Question Bank + AI Help
Hi! Type your question or upload one screenshot. First I will search related questions from CGP Edu Question Bank. If none match, type YES and I will solve it with AI.
Upload only one screenshot at a time. Flow: Question Bank first → If not matched, type YES for AI solution.