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Please answer this question......…………….………………….……….……

Please answer this question......…………….………………….……….……

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Grade:9

1 Answers

NIKHIL GHODKE
55 Points
3 years ago
First of all good question for a ninth grade Nilay!!
we know the formula 
average velocity=(Total DISPLACEMENT)/ total time
btw average dispalcementa and total time lets calculate total time first which the simplest part
total time =Tab+Tbc+Tcd
Tab=time of journey from a → b
ok
total time = 8+11+6 sec
total time is 25 sec
Now we have to calculate total displacement from A to D
so here we come to know that to calculate total displacement we have to calculate Lad
Note total displacement is not equal to total distance 
so total displacement is not equal to Lab+Lbc+Lcd
using s=v*t
we get 
Lab=80(2)1/2
Lbc=5(2)1/2
Lcd =30(2)½
Now some geometry part let us mark a point E on line AB such that Lcd should be equal to Lbe
okay
Lab=Lae+Lbc
      =Lae+Lcd
Lae=Lab-Lcd
from here u can get Lae(we are going to use it )
now AED make a right angled triangle 
ansing phythagoras theorem we  can say that 
(Lae)2+(Led)2=(Lad)2
as we know Led=Lcd and also Lae
we can easily calculate Lad
now we know total displacement and total time u can easily calculate average velocity
 SIMPLE RIGHT
plzz approve my answer Nilay it means a lot to me nd encourages me a lot 
 
Enjoy learning
 

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