Multiple choice

A body covers half the distance with a speed of $20:m/s$ and the other half with $30:m/s$. The average speed of the body during the whole journey is

  1. Zero
  2. $24\:m/s$
  3. $25\:m/s$

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When a journey is divided into two equal distance intervals, the average speed is the harmonic mean of the individual speeds. Using the formula 2 * v1 * v2 / (v1 + v2), we get 2 * 20 * 30 / (20 + 30) = 24 m/s.

AI explanation

Since the body covers equal distances at two different speeds, we use the harmonic mean formula for average speed: 2xy divided by (x + y). Substituting the given speeds gives (2 * 20 * 30) divided by (20 + 30). This simplifies to 1200 divided by 50, resulting in an average speed of 24 m/s.

Keep practicing — related questions