How Do I Find the Derivative of This Vector Function?

In summary, the derivative of the vector function r(t)=ta X (b+at) is given by r'(t) = a X (b+ct) + a X ct, which simplifies to r'(t) = a X b + 2a X ct.
  • #1
megr_ftw
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Homework Statement


Find the derivative of the vector function
r(t)=ta X (b+at)
where a=<4,5,2>, b=<1,-3,2>, and c=<4,3,1>


Homework Equations





The Attempt at a Solution


I know how to take the derivative and everything but the way this question is worded confuses me!
I'm assuming the X means cross product? but it may just mean multiply. Do I plug in the values of a,b,c, and then do what with all the t's?
 
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  • #2
I'm pretty sure X means cross product. People generally don't use X to mean ordinary multiplication at the calculus level.

Yes, substitute the values for a, b, and c, and then carry out the cross product. You'll end up with either (...)i + (...)j + (...)k or <..., ..., ...>, both of which will have terms with t in them. To get r'(t), just take the derivative of each of the three components.
 
  • #3
should I distribute the t to the a values?
 
  • #4
Yes. t is a scalar, so ta = <4t, 5t, 2t>. at is the same as ta.
 
  • #5
Don't carry out the product! Just use the product rule for vector multiplication:
[itex]\vec{f}= \vec{a}t\times (\vec{b}+\vec{c}t[/itex])

so [itex]\vec{f}'= \vec{a}\times (\vec{b}+ \vec{c}t)+ \vec{a}t \times \vec{c}= \vec{a}\times\vec{b}+ 2\vec{a}\times\vec{c}t[/itex].
 

Related to How Do I Find the Derivative of This Vector Function?

1. What is a derivative of a vector function?

A derivative of a vector function is a mathematical operation that calculates the rate of change of a vector function with respect to its independent variable. It tells us how much the vector changes in a certain direction when the independent variable changes.

2. How is the derivative of a vector function different from the derivative of a scalar function?

The derivative of a vector function is a vector, while the derivative of a scalar function is a scalar. This means that the derivative of a vector function has both magnitude and direction, while the derivative of a scalar function only has magnitude.

3. What is the notation used to represent the derivative of a vector function?

The derivative of a vector function is represented using the prime notation, where a prime symbol (') is placed above the vector function. For example, if the vector function is denoted as f(t), its derivative would be written as f'(t).

4. How is the derivative of a vector function calculated?

The derivative of a vector function is calculated by taking the derivative of each component of the vector function with respect to the independent variable. This means that if the vector function is denoted as f(t) = (x(t), y(t), z(t)), its derivative would be f'(t) = (x'(t), y'(t), z'(t)).

5. What is the physical significance of the derivative of a vector function?

The derivative of a vector function has a physical significance in terms of velocity and acceleration. The derivative of a position vector function gives us the velocity vector, and the derivative of the velocity vector function gives us the acceleration vector. In essence, the derivative of a vector function tells us about the rate of change of a physical quantity in a particular direction.

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