Multiple choice

A particle moves along x-axis with speed $6 m/s$ for the first half distance of a journey and the second half distance with a speed $3 m/s$. the average speed in the total journey is

  1. $5 m/s$
  2. $4.5 m/s$
  3. $4 m/s$
  4. $2 m/s$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Average speed = Total distance / Total time. Let total distance be 2d. Time 1 = d/6, Time 2 = d/3. Total time = d/6 + d/3 = 3d/6 = d/2. Average speed = 2d / (d/2) = 4 m/s.

AI explanation

Using the harmonic mean formula for average speed when equal distances are travelled at different speeds, we calculate 2xy divided by (x plus y). Substituting the given speeds of 6 m/s and 3 m/s, the average speed is 2 multiplied by 6 multiplied by 3, divided by the sum of 6 and 3. This simplifies to 36 divided by 9, giving the result 4 m/s.

Keep practicing — related questions