Question

solve any 4 question of this picture

Answer 1

1. Here use a simple formula 
 TO convert km/hr to m/s  : multiply the value in km/hr by 5/18
 TO convert m/s to km/hr  :multiply the valu in m/s by 18/5

SO here to covert km/hr to m/s:
 72 × 5/18 =  20m/s
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2.
Since here the value of length of train and bridge is in metre we have to convert the speed 36km/hr to m/s   {use the above meathod } 

36km/hr=10m/s

Speed=DIstance/time
Time=distance/speed

we have speed = 10m/s

Distance=240m
 
why 240 m? 
Because we say the train has crossed bridge only when even the back part of the train crosses the bridge hence in the distance the length of train will also add up.

hence from the formula of time (above)
Time=240/10
       =24 sec
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3. Speed= distance/time
              
  distance=3.6km    (or)  3600 m   (or)  360000 cm

  time= 1 hr       (or)60 min       (or)  3600 sec

speed in km/hr             {consider the values in km and hour from above}
speed = 3.6/1  = 3.6km/hr


Speed in m/s            {consider the values in metre and sec from above}
speed = 3600/3600 =1 m/s


Speed in cm/s               {consider the values in cm and sec from above}
Speed= 360000/3600 = 100 cm/s

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4. moving faster refers to having higher speed.
 To determine that get both the value of speed to m/s

Speed of scooter = 300m/min = 300m/60sec =5m/s

Speed of car=36km/hr =36000m/ 60*60 sec =36000/3600 = 10m/s

Hence the card is moving with higher speed and is faster than the scooter.
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