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⚛️ Physics  ·  Motion in a Straight Line  ·  NEET & JEE

Rain falls vertically. To a man walking at 4 km/h, the rain appears to come at 30° from the vertical. The actual speed of the rain is:

Answer: 4√3 km/h.

  • A 4√3 km/h
  • B 4/√3 km/h
  • C 8 km/h
  • D 2√3 km/h

Correct answer: A. 4√3 km/h

Explanation: tan30° = 4/v<sub>rain</sub> → v<sub>rain</sub> = 4/tan30° = 4√3 km/h ≈ 6.9 km/h.

tvuvTΔtΔvslope = aarea = displacement (s)

On a velocity-time graph for uniform acceleration, the slope of the line gives the acceleration and the shaded area under the line gives the displacement.

Concept context

Equations of motion, projectile motion, relative velocity. Foundation of all mechanics.

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