An Engine length 1000 m moving at 10 m/s. A bird is flying from engine to end with x kmph and coming back at 2x. Take total time of bird traveling as 187.5 s. Find x and 2x.

• suppose birds speeds in mtrs/sec is s and 2s .
  While flying from Engine to end, relative speed = (s+10) m/sec
  from end to engine, flying speed = (2s-10) mtr/sec
  so
  1000/(s+10) + 1000/(2s-10) = 187.5 secs
  solving it, we get
  so s= 8.728 m/sec and 2s= 17.456 m/sec
• 11 years agoHelpfull: Yes(36) No(10)
• total velocity is 1000/3x = 187.5s
  x=0.5625m/s...
  
• 9 years agoHelpfull: Yes(1) No(4)
• Ans:
  x
  =
  31.43
  x=31.43 km/hr
  2
  x
  =
  62.86
  2x=62.86 km/hr
  
  Let bird is flying from engine to end with
  y
  y m/s and coming back at
  2
  y
  2y m/s
  
  Relative speed when bird is flying from engine
  =
  y
  +
  10
  =y+10 m/s
  Relative speed when bird is coming back to engine
  =
  2
  y
  −
  10
  =2y−10 m/s
  
  Total time taken by the bird = 187.5 s. Therefore,
  1000
  y
  +
  10
  +
  1000
  2
  y
  −
  10
  =
  187.5
  1000y+10+10002y−10=187.5
  
  1000
  (
  2
  y
  −
  10
  )
  +
  1000
  (
  y
  +
  10
  )
  1000(2y−10)+1000(y+10)
  =
  187.5
  (
  y
  +
  10
  )
  (
  2
  y
  −
  10
  )
  =187.5(y+10)(2y−10)
  
  1000
  (
  2
  y
  −
  10
  +
  y
  +
  10
  )
  1000(2y−10+y+10)
  =
  187.5
  (
  2
  y
  2
  −
  10
  y
  +
  20
  y
  −
  100
  )
  =187.5(2y2−10y+20y−100)
  
  1000
  (
  3
  y
  )
  =
  187.5
  (
  2
  y
  2
  +
  10
  y
  −
  100
  )
  
  3000
  y
  =
  375
  y
  2
  +
  1875
  y
  −
  18750
  
  375
  y
  2
  −
  1125
  y
  −
  18750
  =
  0
  
  y
  2
  −
  3
  y
  −
  50
  =
  0
  
  y
  =
  3
  ±
  √
  9
  +
  200
  2
  =
  3
  ±
  √
  209
  2
  
  =
  3
  ±
  14.46
  2
  =
  8.73
  1000(3y)=187.5(2y2+10y−100) 3000y=375y2+1875y−18750 375y2−1125y−18750=0 y2−3y−50=0 y=3±9+2002=3±2092 =3±14.462=8.73
  
  i.e., bird is flying from engine to end with 8.73 m/s
  =
  8.73
  ×
  18
  5
  =
  31.43
  =8.73×185=31.43 km/hr
  
  =>
  x
  =
  31.43
  x=31.43 km/hr
  
  2
  x
  =
  31.43
  ×
  2
  =
  62.86
  2x=31.43×2=62.86 km/hr
• 7 years agoHelpfull: Yes(0) No(2)