A car is moving at a constant speed of 40km/h along a straight road which heads towards a large vertical well and makes a sharp 90 degree turn by the wall .a fly flying at a constant speed of 100km/h, starts from the wall towards the car at an instant when the car is 20km away, flies until it reaches the glass pane of the car and returns to the wall at same speed. it continues to fly between the car and the wall till the car makes the 90 degree turn .
(a) what is the total distance the fly has travelled during this period?
(b) how many trips has it made between the car and the wall?
A car is moving at a constant speed of 40km/h along a straight road which heads towards a large vertical well and makes a sharp 90 degree turn by the wall .a fly flying at a constant speed of 100km/h, starts from the wall towards the car at an instant when the car is 20km away, flies until it reaches the glass pane of the car and returns to the wall at same speed. it continues to fly between the car and the wall till the car makes the 90 degree turn .
(a) what is the total distance the fly has travelled during this period?
(b) how many trips has it made between the car and the wall?
Asked by Jagriti
| 19th Jun, 2017,
09:53: AM
Expert Answer:
(a) First, calculate the time taken by the car to travel the distance of 20 km before the turn.Using the value of the time taken in the above case and also the speed of the car as 100 km/h, calculate the total distance covered.
(b) Suppose the car is at a distance say x km away from the wall at point A when the fly is at the wall (point O).
The fly hits the glass pane at point B, taking time t, then we have
AB − (40 km/hr)t and OB − (100 km/hr)t
→ x = AB + OB − (140 km/hr) t
The fly now returns to the wall and during the time the car moves the distance BC.
The time taken by the fly in the return path is given as
If at the start of the round trip the car is at a distance x away than it is [93/70x] away when the next trip again begins.
Distance of the car at the start of the 1st trip = 20 km
→ Distance of the car at the start of the 2nd trip = (3/7) × 20 km
→ Distance of the car at the start of the 3rd trip = (3/7)2 × 20 km
→ Distance of the car at the start of the nth trip = (3/7)n-1 × 20 km
Trips will continue till the car reaches the turn where the distance reduces to zero.
This will be the case when n becomes infinity.
Thus, the fly makes an infinite number of trips before the turn.
(a) First, calculate the time taken by the car to travel the distance of 20 km before the turn.Using the value of the time taken in the above case and also the speed of the car as 100 km/h, calculate the total distance covered.
(b) Suppose the car is at a distance say x km away from the wall at point A when the fly is at the wall (point O).
The fly hits the glass pane at point B, taking time t, then we have
AB − (40 km/hr)t and OB − (100 km/hr)t
→ x = AB + OB − (140 km/hr) t


→ Distance of the car at the start of the 3rd trip = (3/7)2 × 20 km
→ Distance of the car at the start of the nth trip = (3/7)n-1 × 20 km
Trips will continue till the car reaches the turn where the distance reduces to zero.
This will be the case when n becomes infinity.
Thus, the fly makes an infinite number of trips before the turn.
Answered by Yashvanti Jain
| 20th Jun, 2017,
02:33: PM
Concept Videos
- what is vector quantities
- ar Covers 50km in 15 mins and then covers 65km in next 15 mins. calculate it's average speed
- a car is moving with the acceleration 2m/s from rest find the distance traveled by the car in 10th second
- A car travells 33 km south 13 km west and 14 km north in half an hour calculate the average velocity
- briefly explain different type of motions
- in 12 minute a car whose speed is 35km/hr travel with a distance of
- Abdul, while driving to school, computes the average speed for his trip to be 20 km/h. On his return trip along the same route, there is less traffic and the average speed is 30 km/h. What is the average speed of Abdul's trip?
- what is angular velocity
- A car travels with speed 30km /h for 30mins .and then with speed 40km/h for one hour find the total distance traveled by the car
- two men approach each other from opposite direction with velocity 10m/s and 15m/s . If their initial separation was 150m when and where will they meet?
Kindly Sign up for a personalised experience
- Ask Study Doubts
- Sample Papers
- Past Year Papers
- Textbook Solutions
Sign Up
Verify mobile number
Enter the OTP sent to your number
Change