Multiple choice

A car is moving at a constant speed of 40 km/h along a straight road which heads towards a large vertical wall and makes sharp $90^0$ turn by side of the wall. A fly flying at a constant speed of 100 km/h , starts from the wall towards the car at an instant when the car is 20 km away, flies until it reaches the glasspane of the car and returns to the wall at the same speed. It continues to fly between the car and the wall toll the car makes the $90^0$ turn. What is the total distance the fly has travelled during this period?

  1. 20 km

  2. 30 km

  3. 50 km

  4. 70 km
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The car travels 20 km at 40 km/h, taking 0.5 hours. During this time, the fly flies at 100 km/h. Total distance = speed * time = 100 * 0.5 = 50 km.

AI explanation

The fly travels back and forth only until the car reaches the wall, so the total time of flight equals the time the car takes to cover 20 km at a constant speed of 40 km/h. Using the formula time equals distance divided by speed, the time is 20 divided by 40, which is 0.5 hours. The total distance the fly travels is its speed multiplied by this time, giving 100 km/h times 0.5 h. The total distance is 50 km. The result is 50 km.

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