Question

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?

• A. 20 km
• B. 30 km
• C. 50 km
• D. 70 km

Answer 1

Answer: (C)

50 km

Time taken by car to reach the wall $=\frac{distance}{spee{d}_{car}}$$=\frac{20km}{40km/h}$$=0.5h$

This is the total time for which the fly travels with speed $100km/h$.

Hence, the total distance traveled by fly $=spee{d}_{fly}\times t$$=100km/h\times 0.5h=50km$