Kinematics Question 403

Question: Let A, B, C, D be points on a vertical line such that AB = BC = CD. If a body is released from position A, the times of descent through AB, BC and CD are in the ratio.

Options:

A) $ 1:\sqrt{3}-\sqrt{2}:\sqrt{3}+\sqrt{2} $

B) $ 1:\sqrt{2}-1:\sqrt{3}-\sqrt{2} $

C) $ 1:\sqrt{2}-1:\sqrt{3} $

D) $ 1:\sqrt{2}:\sqrt{3}-1 $

Show Answer

Answer:

Correct Answer: B

Solution:

$ \text{S=AB=}\frac{1}{2}g{{t} _{1}}^{2} $
$ \Rightarrow \text{2S=AC=}\frac{1}{2}g{{( {{t} _{1}}\text{+}{{t} _{2}} )}^{2}} $

$ \text{and 3S = AD = }\frac{1}{2}G{{( {{t} _{1}}\text{+}{{t} _{2}}+t _{3} )}^{2}} $

$ t _{1}=\sqrt{\frac{2S}{g}} $

$ {{t} _{1}}\text{+}{{t} _{2}}=\sqrt{\frac{4S}{g}},t _{2}=\sqrt{\frac{4S}{g}}-\sqrt{\frac{2S}{g}} $

$ {{t} _{1}}\text{+}{{t} _{2}}+t _{3}=\sqrt{\frac{6S}{g}},t _{3}=\sqrt{\frac{6S}{g}}-\sqrt{\frac{4S}{g}} $

$ {{t} _{1}}\text{:}{{t} _{2}}\text{:}{{t} _{3}}::1:( \sqrt{2}-\sqrt{1} ):( \sqrt{3}-\sqrt{2} ) $



जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक