There is a circular track of length 400 mts. If A and B Starts at the same point but in opposite direction with a speeds of 8 m/sec and 12 m/s respectively.Then at what time after the begining they will meet for the second time.
A. 1hr 40 sec
B. 20 sec
C. 40sec
D. 3hr 20 sec

• a & b travel 8+12 = 20 m evry sec..so 400 m will take 20 sec.. for meeting twice 40 sec.. ans C
• 11 years agoHelpfull: Yes(15) No(0)
• average speed = (8+12)/2 = 10m/s
  time = distance/speed
  = 400/10 = 40 sec..............
• 10 years agoHelpfull: Yes(8) No(2)
• B. 20 sec
  
  At 20 sec, A reaches = 8m/sec * 20sec
  = 160mts
  At 20 sec, B reaches = 12m/sec * 20sec
  = 240mts
  S0, both meet at 20 secs = 160 + 240 = 400mts
• 12 years agoHelpfull: Yes(2) No(11)
• opposite direction so speed=12+8=20 m/s
  1st meet 20s , 2nd 40s
• 10 years agoHelpfull: Yes(2) No(0)
• formula:
  time taken=length/speed
  length=400
  speed=20(since they move in opposite dirction)
  time taken=400/20=20
  2nd time =20*2=40
• 9 years agoHelpfull: Yes(2) No(0)
• 40 second.....
• 9 years agoHelpfull: Yes(1) No(0)
• A completes 160m in 20 seconds with 8m/s, 8m/s * 20 sec=160mts,
  B completes 240m in 20 seconds with 12m/s, 12m/s * 20 sec=240mts,
  so A & B meets in 20 sec
• 9 years agoHelpfull: Yes(1) No(2)