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MHT CET 2026 (12 May, Shift 1) · Relative Velocity in Two Dimensions

Relative Velocity in Two Dimensions question from MHT CET 2026 (12 May, Shift 1)

Q4MHT CET 2026 · 12 MAY · SHIFT 1Difficult

Relative Velocity in Two Dimensions

Airplanes A and B are flying with constant velocity in the same vertical plane at angles 30∘30^\circ and 60∘60^\circ with respect to the horizontal as shown in the figure. The speed of A is 1003100\sqrt{3} m/s. At time t=0t = 0 s, an observer in A finds B at a distance of 500500 m. This observer sees B moving with a constant velocity perpendicular to the line of motion of A. If at t=t0t = t_0, A just escapes being hit by B, t0t_0 in second is

{sin⁡(30∘)=0.5,cos⁡(30∘)=30.5/2}\{\sin(30^\circ) = 0.5, \cos(30^\circ) = 3^{0.5}/2\}

Figure

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Answer: (d)

  1. B is seen moving perpendicular to A's path, so the component of v⃗B\vec v_B along A's direction equals vAv_A.
  2. Angle between the two paths is 60∘−30∘=30∘60^\circ - 30^\circ = 30^\circ: vBcos⁡30∘=1003⇒vB=200v_B\cos 30^\circ = 100\sqrt{3} \Rightarrow v_B = 200 m/s.
  3. Relative speed (perpendicular to A's path) =vBsin⁡30∘=200×0.5=100= v_B\sin 30^\circ = 200 \times 0.5 = 100 m/s.
  4. t0=500100=5t_0 = \dfrac{500}{100} = 5 s
  5. So the answer is (d) 55.
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