Avg velocity problem/ puzzle

A train goes around a circle, the first time with an average velocity of 100 km/h. How fast should the train be when going around the circle again a second time, so that the average velocity over the two loops is 200 km/h?

6 Answers

1
saurabh goel ·

300Km/hr

(300+100)/2 = 200

1
Ashish Sharma ·

No saurabh...
It is not 200

It has to come as total distance by total time.

Total distance will be 2PiR x 2
let 2PiR=D

Total Time will be D/100 + D/x = D(1/100+1/x)

Total time when traveling two circles by 200km/h, = 2D/200

2D/200 = D(1/100+1/x)

1/100 = (1/100+1/x)

so , 1/x = 0

but i dont know what to do aftet this.. i m feeling stuck!!

I mean i cant find any mistake in my solution still there is no solution. :(

1
saurabh goel ·

Does it not only mean that this is not possible!!!

i mean no matter how fast he travelled he will not make it!

33
Abhishek Priyam ·

Avg Velocity around the circle is Zero net diisplacement=0. Will not speed be the right word. We should not compromise wiyh basic definitions.
Waise Main apki Bhavnao ko samajh raha hun ki aap kya bolna chah rahe hain......

Jo maine pahle kaha tha: Maths ∞ ko catch nahi karta hai par Hint de deta hai, isme bhi hint de raha hai. all the time required is consumed in first round so no time is left 4 second round.Whatever be the speed one can't make it.

1
Vyom Parashar ·

yes... you have caught me napping :)

1
Vyom Parashar ·

and ur solution is absolutely perfect.. (not just hinting it :P)

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