Physics Two Dimensional Motion Question 190

Question: Two particles are projected simultaneously from the level ground as shown in figure. They may collide after a time:

Options:

A) $ \frac{x\sin {\theta _{2}} _{}}{u _{1}} $

B)$ \frac{x\text{ cos}{\theta _{2}} _{}}{u _{2}} $

C) $ \frac{x\sin {\theta _{2}} _{}}{u _{1}\sin ( {\theta _{2}}-{\theta _{1}} )} $

D)$ \frac{x\sin {\theta _{1}} _{}}{u _{2}\sin ( {\theta _{2}}-{\theta _{1}} )} $

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Answer:

Correct Answer: C

Solution:

[c] $ x+u _{2}\cos {\theta _{2}}t=u _{1}\cos {\theta _{1}}t $ $

Therefore $t=\frac{x}{u _{1}\cos {\theta _{1}}-u _{2}\cos {\theta _{2}}} $ …(i)

Also $ u _{1}\sin {\theta _{1}}=u _{2}\sin {\theta _{2}} $ …(ii)

After solving above equations, we get

$t = \frac{x \sin \theta_2}{u_1 \sin (\theta_2 - \theta_1)}$