Multiple choice

A particle moving in a straight line covers half the distance with a speed of 3m/s. The other half of distance is covered with double speed 6m/s. The average sped of the particle is:

  1. 4.5 m/s

  2. 4 m/s

  3. 9 m/s

  4. 5 m/s
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B Correct answer
Explanation

Average speed = Total distance / Total time. Let total distance be 2d. Time = d/3 + d/6 = 3d/6 = d/2. Average speed = 2d / (d/2) = 4 m/s.

AI explanation

When a particle covers equal distances at two different speeds, its average speed is given by the harmonic mean formula: 2uv divided by (u + v). Substituting the given speeds of 3 m/s and 6 m/s, the calculation is 2 times 3 times 6 divided by (3 + 6). This gives 36 divided by 9, which equals 4 m/s.

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