Kinematics Question 652

Question: A boat B is moving upstream with velocity 3 m/s with respect to ground. An observer standing on boat observes that a swimmer S it’s crossing the river perpendicular to the direction of motion of boat. If river flow velocity is 4 m/s and swimmer crosses the river of width 100 m in 50 sec, then

Options:

A) velocity of swimmer w.r.t ground it’s 13m/s

B) drift of swimmer along river is zero

C) drift of swimmer along river will be 50 m

D) velocity of swimmer w.r.t ground it’s 2 m/s

Show Answer

Answer:

Correct Answer: A

Solution:

[a] vSB=vj^=vs+3i^

vS=vj^3i^ and v=10050=2m/s

|vs| =v2+(3)2=22+9=13 m/s

Drift = 50×3=150 m



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