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Originally Posted by nikunj14_83 Hi all,
Please help me out to solve these TSD problems....
1) A nughty bird is sitting on a car & it see's a car coming towards it at a distance of 12 Km.Th bird moves on from the bonnet of first car to the second car till the two car's crash(Assume that both car's crash). Speed of both car's is 60 Kmph & speed of bird is 120 Kmph.
a)Total distance covered by bird when it reaces the bonnet of second car for the second time?....Ans is 11.55Km
b) Therotically how many times bird reaches the second car?...Ans is Infinite times Both questions are LOD(2) from Arun Sharma |
Distance between cars = 12km
Speeds of cars = 60kmph
Speed of bird = 120 kmph
Speed of bird relative to car = 180kmph(120+60, as they are moving in opposite direction)
Relative speed of cars = 120kmph(60+60)
Now,
when bird moves for bonnet 1 to bonnet 2 for 1st time:
Distnace Betwee cars = 12 km
So,Time taken by bird two move = 12/180
Distance covered by bird = (12/180)*120 = 8km
Distnace covered by cars = (12/180)*120 = 8km
Distance left between cars = 12-8 = 4km
when bird moves for bonnet 2 to bonnet 1 for 1st time:
Distnace Betwee cars = 4 km
So,Time taken by bird two move = 4/180
Distance covered by bird = (4/180)*120 = 8/3km
Distnace covered by cars = (4/180)*120 = 8/3km
Distance left between cars = 4-(8/3) = 4/3 km
when bird moves for bonnet 1 to bonnet 2 for 2nd time:
Distnace Betwee cars = 4/3 km
So,Time taken by bird two move = (4/3)/180
Distance covered by bird = [(4/3)/180]*120 = 8/9 km
So total distance covered by bird in whole journey = 8 + 8/3 + 8/9 =
11.55 km
Also as the distance remianing between two cars(theoritically) will keep reducing by ver very small amount for more number of trips....so theoritically bird can make infinite trips..