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# Change in velocity? Watch

1. When drawing a vector diagram, I have been told to use the tip-to-tail rule

However, as per this attachment, the change in velocity (which is a vector) does not seem to use this rule. indeed change in v (the horizontal line) has magnitude VB - Va.

Why is this?
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2. (Original post by ilovemath)
When drawing a vector diagram, I have been told to use the tip-to-tail rule

However, as per this attachment, the change in velocity (which is a vector) does not seem to use this rule. indeed change in v (the horizontal line) has magnitude VB - Va.

Why is this?
It is using the tip-tail rule, it's just you're adding the wrong way round.

Tip to tail is for a+b=c with the tails of a and c starting at the origin, and the tip of a and the tail of b coinciding, and the tips of b and c coinciding.

for change in velocity the equation is va+dv=vb and as you can see from your diagram the tip of va and tail of dv do coincide
3. (Original post by The Mr Z)
It is using the tip-tail rule, it's just you're adding the wrong way round.

Tip to tail is for a+b=c with the tails of a and c starting at the origin, and the tip of a and the tail of b coinciding, and the tips of b and c coinciding.

for change in velocity the equation is va+dv=vb and as you can see from your diagram the tip of va and tail of dv do coincide
oh I see

Updated: June 2, 2012
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