How Do You Calculate Force in Vector Form?

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To calculate force in vector form, first determine the unit vector by dividing the vector (1, 1, 1) by its length. The force can then be expressed as a vector by multiplying the magnitude of the force (14 N) by the unit vector, resulting in the expression {14/√3}i + {14/√3}j + {14/√3}k. For further calculations, the dot product of two vectors can be found using the formula A·B = AxBx + AyBy + AzBz. The discussion clarifies the process of expressing force in vector form and performing dot products. Understanding these concepts simplifies the calculation of force in physics.
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Hi everyone

please help
how can i find the force in Q(a)(ii)?

WhatsApp Image 2016-12-11 at 9.58.01 PM.jpeg
 
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Welcome to PF William!

A unit vector is just the vector ie. (x, y z) divided by its length. What is the length of this vector (1,1,1)?

You must then express the force as a vector by multiplying the magnitude of tbe force (14 N) by the unjt vector in the direction of that force.

Can you provide us with the expression for Work in terms of the information provided?

AM
 
like this?
but how can get force of vector by multiplying
WhatsApp Image 2016-12-11 at 11.28.24 PM.jpeg
 
williamwong0402 said:
but how can get force of vector by multiplying
I did not get it. Can you please state it clearly.
But I guess you mean how to express Force in vector form. That is simply ##{14\over\sqrt{3}}\hat{i} + {14\over\sqrt{3}}\hat{j} +{14\over\sqrt{3}}\hat{k}##.

For (iv) you need to take dot product of (ii) and (iii). ##(\vec{A}\cdot\vec{B} = A_xB_x + A_yB_y + A_zB_z)##
 
Buffu said:
I did not get it. Can you please state it clearly.
But I guess you mean how to express Force in vector form. That is simply ##{14\over\sqrt{3}}\hat{i} + {14\over\sqrt{3}}\hat{j} +{14\over\sqrt{3}}\hat{k}##.

For (iv) you need to take dot product of (ii) and (iii). ##(\vec{A}\cdot\vec{B} = A_xB_x + A_yB_y + A_zB_z)##

Thank you ~i got it
i just thought the other way more complex:wink:
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks

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