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Old Jul 19th 2019, 08:37 PM   #1
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Vector

How to solve Q3.
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Old Jul 20th 2019, 06:15 AM   #2
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Do you know what the word "resultant" means?
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Old Jul 20th 2019, 08:41 AM   #3
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Originally Posted by HallsofIvy View Post
Do you know what the word "resultant" means?
Yes, resultant is the combined effect of two vectors. Am I correct?
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Old Jul 20th 2019, 10:22 AM   #4
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Yes, so the "C" they refer to is the length |A+ B|. What is the relation between |A+ B| and |A- B|?
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Old Jul 20th 2019, 11:26 PM   #5
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Originally Posted by HallsofIvy View Post
Yes, so the "C" they refer to is the length |A+ B|. What is the relation between |A+ B| and |A- B|?
I don't understand the relation But as I know C = A + B (positive direction)
C = A - B A is in the positive direction and B is in the negitive direction
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Old Jul 21st 2019, 07:46 AM   #6
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Originally Posted by HallsofIvy View Post
Yes, so the "C" they refer to is the length |A+ B|. What is the relation between |A+ B| and |A- B|?
A+B is greater than A-B?
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Old Jul 21st 2019, 08:50 AM   #7
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No, that is not necessarily true. First, do you understand the difference between "A+ B" and "|A+ B|"? Do you understand that for vectors, like A+ B and A- B, "less than" and "greater than" are NOT defined?
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Old Jul 21st 2019, 08:56 PM   #8
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Originally Posted by HallsofIvy View Post
No, that is not necessarily true. First, do you understand the difference between "A+ B" and "|A+ B|"? Do you understand that for vectors, like A+ B and A- B, "less than" and "greater than" are NOT defined?
A+B is the addition of two vectors and [A+B] is the magnitude of two vectors (addition of numbers) Am I right?
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Old Jul 22nd 2019, 06:40 PM   #9
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Yes, that is correct. And while you cannot say, of two vectors A and B, that "A< B" or "B< A", you can say that |A|< |B| or |B|< |A|.

But given two vectors (or even numbers) you cannot say "|A+ B|> |A- B|. For example, if B= -A then |A+ B|= 0 while |A- B|= 2|A|.
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Old Jul 22nd 2019, 07:32 PM   #10
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Originally Posted by HallsofIvy View Post
Yes, that is correct. And while you cannot say, of two vectors A and B, that "A< B" or "B< A", you can say that |A|< |B| or |B|< |A|.

But given two vectors (or even numbers) you cannot say "|A+ B|> |A- B|. For example, if B= -A then |A+ B|= 0 while |A- B|= 2|A|.
Good catch. I hadn't thought of that.

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