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October 22, 2025, 12:46:31 am
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Author Topic: Calculating speed using velocity vector  (Read 618 times)  Share 

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sajib_mostofa

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Calculating speed using velocity vector
« on: October 12, 2010, 12:12:30 am »
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When calculating the speed at a certain time with the velocity vector given, should you sub the t value and then find the magnitude or is it the other way around?
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TrueTears

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Re: Calculating speed using velocity vector
« Reply #1 on: October 12, 2010, 12:14:34 am »
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speed is the magnitude of the velocity vector.

Thus you sub in the value of t into the velocity vector, then find the magnitude.
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sajib_mostofa

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Re: Calculating speed using velocity vector
« Reply #2 on: October 12, 2010, 12:23:48 am »
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ahh yep cheers for that. I've always found the magnitude and then tried to sub in the value of t, which has given me really complex expressions sometimes..
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TrueTears

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Re: Calculating speed using velocity vector
« Reply #3 on: October 12, 2010, 12:24:58 am »
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haha yeah, because if you sub in the values of t first, you reduce v(t) down into a vector with constant 'coefficients' so easier to find magnitude :D
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Martoman

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Re: Calculating speed using velocity vector
« Reply #4 on: October 12, 2010, 08:22:03 pm »
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eh when you have something like

acos(x)i + asin(x) as v(t)

its just aroot(1) = a

So when you have nice trig functions which evaluate nicely to 1 then you can use this quickly.
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