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Two particles having position verctors v...

Two particles having position verctors `vecr_(1)=(3hati+5hatj)` metres and `vecr_(2)=(-5hati-3hatj)` metres are moving with velocities `vecv_(1)=(4hati+3hatj)m//s and vecv_(2)=(alphahati+7hatj)m//s`. If they collide after 2 seconds, the value of `alpha` is

A

2

B

4

C

6

D

8

Text Solution

Verified by Experts

The correct Answer is:
D
(d): Particles will collide if their position at time t is same
`rArr vecr_(1)+vecv_(1)t=vecr_(2)+vecv_(2)t`
`(3hati+5hatj)+(4hati+3hatj)xx2=(-5hati-3hatj)+(ahati+7hatj)xx2`
`(+5hati+3hatj)+11hati+11hatj=(a hati+7hatj)2`
`16hati+14hatj=2ahati+14hatj rArr a=8`
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