Time and speed shortcuts-Part 1

Time, Speed and Distance


Time and speed shortcuts-Part 1

Basics:
      Speed     =  Distance / Time
      Time       =   Distance / Speed
     Distance  =   Speed * Time
For conversion of Km/hr to m/sec and as well as m/sec to km/hr
  • For km/hr to m/sec    =  we need multiply with 5/18
  • For m/sec to km/hr    =  we need multiply with 18/5
If u need clear info about conversion you can comment below

Ex:-
1. A person crosses a 600 m long street in 5 minutes. what is his speed in km/hr?

Ans: 
      D= 600m 
      T= 5min
       S=? in km/hr
 In this, we can’t do the direct calculation because speed in meters and Time in minutes so we need to convert anyone either speed into km or Time into sec or hr
  •     Time = 5*60
                      = 300sec
  •     Speed=Distance/Time  
                       = 600/5
                       = 120
                       = 2 m/s
 But this is not answer for the above question this is the mistake that most of the people doing in exams
Because it is m/sec but we need km/hr so we need to convert it.
             km/hr=  2*(18/5)
                      =   72km/hr
2. If a person walks at 14 km/hr instead of 10km /hr, he would have walked 20km more. The actual distance traveled by him is?

Ans: 
     For the speed at 10 km/hr the assume distance D and as well as at 14 km/hr he would be walked 20km more So D2=D+20

   Given Data :
          D  =D
          T  =T
          D2=  D+20

    Here time for the both speeds are same so we can use the formula
     

      (D/S1)=((D+20)/S2)
        by solving above   7D=5D+100
                                        7D-5D=100   =>   2D=100
                                          Distance D= 100/2   => 50km



India

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