CET Karnataka Medical
CET - Karnataka Medical Solved Paper-2013
question_answer
A projectile is projected at \[10\text{ }m{{s}^{-1}}\]cby making at an angle \[{{60}^{o}}\] to the horizontal. After some time its velocity makes an angle of \[{{30}^{o}}\] to the horizontal. Its speed at this instant is
A) \[\frac{10}{\sqrt{3}}\]
B) \[10\sqrt{3}\]
C) \[\frac{5}{\sqrt{3}}\]
D) \[5\sqrt{3}\]
Correct Answer:
A
Solution :
: Let \[\upsilon \] be the velocity of the projectile at P when it makes an angle \[{{30}^{o}}\] with the horizontal. Then \[\upsilon \,\cos {{30}^{o}}=u\cos {{60}^{o}}=10\times \frac{1}{2}=5\] \[\upsilon =\frac{5}{\cos {{30}^{o}}}=\frac{5}{(\sqrt{3}/2)}=\frac{10}{\sqrt{3}}m\,{{s}^{-1}}\]