Two particles are fired together along a smooth horizonta...
Two particles are fired together along a smooth horizontal surface with velocities 4 m/s and 5 m/s. If they move at 60° to each other, find the distance between them in 2 seconds.
2√61
√42
2√21
2√10
Correct answer is C
Given lines OA and OB inclined at angle θ, the line AB is gotten using cosine rule.
|AB|2=|OA|2+|OB|2−2|OA||OB|cosθ
|AB|2=42+52−2(4)(5)cos60
= 16+25−20
|AB|2=21⟹|AB|=√21
⟹The two particles are√21mapart in 1 sec
In two seconds, the particles will be 2√21m apart.
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