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| Question 647319:  if a car accelerates and move at a constant speed of 40km/h and reaches 80 km in 3 hours,and then de accelerates and come back at same speed of 40km/h and reaches 40 km in 3 hours,then what we have done in 6 hours as displacement is zero for the car.
 Answer by Alan3354(69443)
      (Show Source): 
You can put this solution on YOUR website! if a car accelerates and move at a constant speed of 40km/h and reaches 80 km in 3 hours, -----------
 If it moves at 40 km/hr for 3 hours, it won't go 80 km, it'll go 120 km.
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 and then de accelerates and come back at same speed of 40km/h and reaches 40 km in 3 hours,
 40*3 = 120, not 40
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 then what we have done in 6 hours as displacement is zero for the car.
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