Is multiplication associative in physics?

In summary, the conversation discusses the commutativity property in mathematics and its application in physics, specifically in the equations for work. It is noted that while the multiplication of scalars is both associative and commutative, the multiplication of vectors and operators is not always commutative. The conversation concludes that this topic should be discussed in the field of math rather than physics.
  • #1
oahz
13
0
Work = Force X Distance.

? = Distance X Force

How do you make sense of the second equation?
 
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  • #2
For a little displacement ##\vec{dl},## the work the force ##\vec{F}## does is ##\vec{F}\cdot\vec{dl},## which is identical to ##\vec{dl}\cdot\vec{F},## for the commutativity of the vector's scalar product.
But it doesn't happen everywhere in physics. For example, the non-commutativity of matrices finally implies the uncertainty principle.
Edited for getting uncleared at the same time.
 
  • #3
1) You're asking about the commutativity property, not associativity, which is ## (a \times b)\times c=a \times (b\times c)##.
2) The multiplication defined for real numbers is commutative, doesn't matter in what field of science you're considering it. But the more general definition of work is through ## W= \vec F \cdot \vec D ##. So we should talk about the inner product defined on vectors. That is commutative too and again it doesn't matter in what field of science you're considering it.
 
  • #4
oahz said:
Work = Force X Distance.

? = Distance X Force

How do you make sense of the second equation?

Do you mean commutative? (Associative -> a+(b+c) = (a+b)+c, commutative a*b=b*a). https://en.wikipedia.org/wiki/Commutative_property

And physics is associative/commutative when the mathematics you are using is. The rules don't change when you're doing physics. If you multiply scalars, it is associative and commutative. If you are multiplying matrices, it is not commutative in general.
 
  • #5
Yes, I mean commutative.
 
  • #6
oahz said:
Yes, I mean commutative.

Then the answer is yes and no.

A cross product is not commutative. A dot product is.

A vector product is not commutative. A scalar product is.

And the multiplication of operators need not be commutative.

This should be in Math, not Physics.

Zz.
 

1. Is multiplication associative in physics?

Yes, multiplication is associative in physics. This means that the order in which numbers are multiplied does not affect the final result. For example, (2x3)x4 is equal to 2x(3x4).

2. Why is it important to understand the associativity of multiplication in physics?

Understanding the associativity of multiplication is important in physics because many physical laws and equations involve multiplication. If multiplication was not associative, it would lead to different results and potentially incorrect conclusions.

3. Are there any exceptions to the associative property of multiplication in physics?

No, there are no exceptions to the associative property of multiplication in physics. It holds true for all real numbers and is a fundamental property of arithmetic.

4. How does the associativity of multiplication affect calculations in physics?

The associativity of multiplication allows for simplification of calculations in physics. It means that we can group numbers in any way we choose without changing the final result, making complex equations more manageable.

5. Can the associativity of multiplication be proven in physics?

Yes, the associativity of multiplication can be proven mathematically using the laws of arithmetic. It is also supported by numerous experiments and observations in the field of physics.

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