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![[Post New]](/templates/default/images/icon_minipost_new.gif) 12 May 2007 09:17:43 IST
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A motor car is going due north at a speed of 50km/h .It makes a 900 left turn without changing the speed .The change in d velocity of d car is abt a) 50km/h towards west b) 70km/h towards south-west c)70km/h towards north-west d)zero plz tell d correct ans wid explanation.
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12 May 2007 09:24:58 IST
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hi. ok now the change in velocity is v2 - v1
draw the vector diagram. and the resultant should be 70 km/h towards S/W.
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12 May 2007 09:25:42 IST
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how towards north west?????
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12 May 2007 09:31:53 IST
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oh sorry it is actually along S/W my mistake, jus draw d vector diagram & knock if u need more help.
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12 May 2007 15:00:26 IST
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y along S/W?
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12 May 2007 15:33:46 IST
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it shd b 45 degrees right to north
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12 May 2007 16:06:04 IST
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The ans is (b) Initial velocity in vector form = 5j (j represents the unit vector along the +ve x- axis) Final velocity = 5i or 5(-i) because 90o turn means that it turns due west Hence change in vel = -5i-5j =70Km/h due south west
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12 May 2007 16:10:54 IST
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12 May 2007 16:15:46 IST
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The ans is (b)
amit,,, the diagram is correct but shouldnt it be inverted ( left turn )
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<TABLE CELLSPACING="1" CELLPADDING="1" BORDER="0">
<TR><TD>
         
<DIV ALIGN="right">Animated Letters</DIV></TD></TR></TABLE>
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12 May 2007 16:19:38 IST
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it turns 90 degree towards left only joyfrancis
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12 May 2007 16:55:45 IST
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@shikharbaid.
Look it is not inverted it is the resultant of both the changes
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12 May 2007 17:40:17 IST
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hi sneha
according to me the answer is [c]
this is because when the car turns left the resultant would then be in the right( west) direction.........i.e the resultant would have components in the west and the north direction
regarding magnitude applying the paralellogram law of vectors
it would be [ (50)^2 +(50)^2+2(50)(50)cos 90]= 70 km/hr
hence 70 km/ hr noth- west
and ya plz rate if correct do let me know the correct ans if wrong
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everybody has a photographic memory, some lack film...........<TABLE CELLSPACING="1" CELLPADDING="1" BORDER="0">
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13 May 2007 00:59:48 IST
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Oh i got wat u mean @shikharbaid.
I have edited it Funda is same.
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