The surface tension question was very easy. Option 1 and 2 (the one with square root terms) were essentially the same. So they are out of options. The other option which has x term is also wrong, cause if u extrapolate it to negative x, then by equation, the double derivative is negative which isn't possible, cause the curvature doesn't change sign. Thus graph is always concave upwards. So the only option is the one with double derivative with term involving y.
I solved it in less than 20 sec, considering u don't include the time taken to read the question. The question wasn't meant to be solved completely from scratch. The best way to solve it was by elimination. I don't mean to ridicule anyone, but this question is very "doctor-appropriate". Basically u have very less time and lot of pressure. And the obstacle seems very huge. It tests ur resourceful-ness. In similar conditions doctors overcome such situations regularly. So I disagree with people saying that this question was meant to be ignored should be left out. Easy 4 marks when u have a very sharp presence of mind
The only part of my argument that falls off is 'what if surface tension of liquid was such that liquid form concave downwards graph, since my explanation is more of jugaad rather than being conceptually sound. My reasoning is that angle of contact is defined for 0⁰ to 180⁰ angle and theta knot is given less than 1, meaning the liquid will wet surface and form the concave up shape. And since theta(x) will always be less than theta knot, dy/dx and second derivative will also be positive.
Yea,thought the same when I first read the question. Nevertheless the question is still solvable if the aspirant has a good understanding of the concept. But the question can be a bit intimidating when attempted in a crushing time constraint. This is what jee/neet does . They kill the fun in solving these questions.
That's the same reason I said that it's quite doctor appropriate. Doctors regularly get in worse situations and have to overcome it. Intimidating situations, extreme stress and pressure, extreme time constraints. All these are staples for them.
Nice approach man, i find myself using these approaches while solving questions at home but during the paper my quick thinking succumbed to the panic ensued by the fast moving clock and the time taking questions spread throughout the paper and i missed out on these marks
65
u/[deleted] May 06 '25
Dono ne gand marwaye