Multiple choice

Two motorcycles $M_{1}$ and $M_{2}$ are heading towards each other with a speed of $30 kmh^{-1}$ each. A bird flies off $M_{1}$ at $60 kmh^{-1}$ when distance between the motorcycles is $60 km$. It heads towards $M_{2}$ and then back to $M_{1}$ and so on. The total distance the bird moves till the motorcycles meet is

  1. $60 \:km$
  2. $40 \:km$
  3. $50 \:km$
  4. $30 \:km$

  5. none
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A Correct answer
Explanation

The motorcycles are 60 km apart and each moves at 30 km/h, so they approach each other at a relative speed of 60 km/h. They will meet in 60 km / 60 km/h = 1 hour. Since the bird flies at a constant speed of 60 km/h for the entire hour, it covers 60 km/h * 1 h = 60 km.

AI explanation

The motorcycles approach each other with a relative speed of 30 km/h plus 30 km/h, totaling 60 km/h. Covering the initial distance of 60 km at this relative speed, the time until they meet is exactly 1 hour. The bird flies continuously at 60 km/h for this entire 1-hour period, meaning the total distance it travels is 60 km.

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