A boy is cycling such that the wheel of his cycle is undergoing 420 revolutions per minute. The diameter of the wheel is 50cm. Find his speed in kmph.

• Ans is 39.6 Kmph
  distance covered in 1 revolution=.25*2*(22/7)=1.57142
  so, distance covered in 7 revolution or in 1 second=1.57142*7=11 (Because there are 7 revolution in 1 second)
  hence speed= 11 m/s or 11*(18/5)= 39.6 kmph
• 11 years agoHelpfull: Yes(39) No(1)
• 1 min= 420 revolutions
  diameter of wheel = 50, so radius will be 25
  or 0.25 m.
  distance covered in 1min= 420*2*pie*25
  =660
  nw in 60 s = 660
  1 s = 11m/s
• 11 years agoHelpfull: Yes(9) No(1)
• total distance covered in 1 minute= 2*pie*r*420
  soving it gives 11m/sec
• 11 years agoHelpfull: Yes(5) No(2)
• 39.6 kmph is the ans
• 11 years agoHelpfull: Yes(4) No(0)
• ans is - 22 m/sec
• 11 years agoHelpfull: Yes(2) No(4)
• howz this.....plse explain it
  
• 11 years agoHelpfull: Yes(0) No(0)
• its 39.564
  revolutions per second is 420/60=7
  total distance traveled is 7*2*pi*d/200 m
  so in kmph multiply the above value by 18/5
  
• 11 years agoHelpfull: Yes(0) No(0)
• (420*50*60)/100000= 12.6kmph
• 11 years agoHelpfull: Yes(0) No(0)
• total distance covered in 1 minute= 2*(22/7)*r*420*(1/60)sec
  soving it gives 11m/sec now covert it into km/h=11*(18/5)
• 11 years agoHelpfull: Yes(0) No(0)
• 39.6 km/hr
• 11 years agoHelpfull: Yes(0) No(0)
• 39.6 should be the ans
• 11 years agoHelpfull: Yes(0) No(0)
• since, in 1 min the revolution= 420
  distance covered in 1 min= 2*pi*r*n i.e 2*22/7*25/100*420
  then speed in m/s= (2*22/7*25/100*420)/60= 11 m/s
  in Kmph= 11*18/5=39.8 Kmph
• 11 years agoHelpfull: Yes(0) No(0)
• 11 m/s answer !!!!
• 11 years agoHelpfull: Yes(0) No(0)