two forces p and q acting at a point are such that if p is reversed , the direction of the resultant is turned through 90 . then p = nQ . find the value of n
Answers
Answer:
Explanation:
N=90*2
180
Hopes
Answer:
The 2 vectors can be represented by:
p = aî + bĵ
q = cî + dĵ
The resultant is q+p = (c+a)î + (d+b)ĵ
If p is reversed it becomes -p. So the new resultant is q-p.
q-p = (c-a)î + (d-b)ĵ
q+p is perpendicular to q-p so their dot (scalar) product is zero:
((c+a)î + (d+b)ĵ) • ((c-a)î + (d-b)ĵ) = 0
(c+a)(c-a) + (d+b)(d-b) = 0
c² - a² + d² - b² = 0
a²+b² = c² + d²
Since ||p||²= a²+b² and ||q||²= c²+d²
||p|| = ||q||
So the magnitude of p must equal the magnitude of q, but p can be in any direction (but see note below).
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Note. There is an exception to the direction of p. p and q can't be parallel or antiparallel, as either p-q or p+q would then be zero. Taking a dot product where one of the vectors is zero is not an allowed operation.
Explanation:
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