Work Energy and Power - Result Question 47
50. Two particles A and B, move with constant velocities $ \vec{v} _1$ and $ \vec{v} _2$. At the initial moment their position vectors are $ \vec{r} _1$ and $ \vec{r} _2$ respectively. The condition for particles $A$ and B for their collision is:
[2015 RS]
(a) $ \vec{r} _1 \cdot \vec{v} _1= \vec{r} _2 \cdot \vec{v} _2$
(b) $ \vec{r} _1 \times \vec{v} _1= \vec{r} _2 \times \vec{v} _2$
(c) $ \vec{r} _1- \vec{r} _2= \vec{v} _1- \vec{v} _2$
(d) $\frac{ \vec{r} _1- \vec{r} _2}{| \vec{r} _1- \vec{r} _2|}=\frac{ \vec{v} _2- \vec{v} _1}{| \vec{v} _2- \vec{v} _1|}$
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Answer:
Correct Answer: 50. (d)
Solution:
- (d) For collision $ \vec{V} _{B / A}$ should be along
$ B \to A(\overrightarrow{{}r} _{A / B}) $
So, $\frac{ \vec{V} _2- \vec{V} _1}{|V_2-V_1|}=\frac{ \vec{r} _1- \vec{r} _2}{|r_1-r_2|}$
