What is the derivative of a vector?

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To find the first derivative of the vector A=(5, 6t, 7t^2), the components are differentiated individually, resulting in A' = (0, 6, 14t). The inclusion of unit vectors is optional; it can be expressed as (0, 6, 14t) or with unit vectors as 0i + 6j + 14tk. The discussion confirms that the derivative calculation is correct. The second derivative can similarly be derived by differentiating A' again.
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I`ve been asked to find the first and second time , t , derivative of a Vector A=(5, 6t, 7t^2)

Ok, now my prof hasn`t given any examples and i don`t have a text bok with these in so i need to ask for a bit of advise.

I`ve been told that all i need to do is find the derivative of the components!

So i`m thinking that;

A` = (0, 6, 14t)

Is this correct?

[edit] OOPs i forgot about the unit vectors, therefore A` = (0, 6j, 14t k)
where the unit vectors i, j, k are the magnitued of the vector along the x, y, z axis[/edit]
 
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You don't need to add the unit vectors if you write it in components like (0,6,14t).
An alternative way is writing 0{\bf{\hat i}} + 6{\bf{\hat j}} + 14t{\bf{\hat k}}

The derivative seems correct :smile:
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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