IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: sweetest angel on March 28, 2010, 04:54:04 pm
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Two forces, (4i – 5j) N and (pi + qj) N, act on a particle P of mass m kg. The resultant
of the two forces is R. Given that R acts in a direction which is parallel to the
vector (i – 2j),
(a) find the angle between R and the vector j,
(b) show that 2p + q + 3 = 0.
Given also that q = 1 and that P moves with an acceleration of magnitude 8?5 m s–2,
(c) find the value of m.
i need someone to xplain part b asap...Thanks :)
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Two forces, (4i – 5j) N and (pi + qj) N, act on a particle P of mass m kg. The resultant
of the two forces is R. Given that R acts in a direction which is parallel to the
vector (i – 2j),
(a) find the angle between R and the vector j,
(b) show that 2p + q + 3 = 0.
Given also that q = 1 and that P moves with an acceleration of magnitude 8?5 m s–2,
(c) find the value of m.
i need someone to xplain part b asap...Thanks :)
how did u do part a?
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tan? = 2/1
?? = 63.4
angle is 90+63.4=153.4
its because it is parallel to (i-2j) so they'l have the same angel
bdw its 2laa2 ya halla :)
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b part, add the 2 vector forces to give the resultant force
the resultant force vector is parallel to the (i-2j) vector, hence gradient will be same
formula is i1/i2 = j1/j2
Ri /i = Rj /-2
4+p/1= q-5/-2
cross multiply to get
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tan? = 2/1
?? = 63.4
angle is 90+63.4=153.4
its because it is parallel to (i-2j) so they'l have the same angel
bdw its 2laa2 ya halla :)
hahhaah mana 3arfa ya otah ;)
thx..am failing mechanics tomorrow -.-"
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b part, add the 2 vector forces to give the resultant force
the resultant force vector is parallel to the (i-2j) vector, hence gradient will be same
formula is i1/i2 = j1/j2
Ri /i = Rj /-2
4+p/1= q-5/-2
cross multiply to get
no i didnt get it :/...why did u divide them by the vector that they are parallel to?
lol haloosh evryone is sayin dat :P
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no i didnt get it :/...why did u divide them by the vector that they are parallel to?
lol haloosh evryone is sayin dat :P
i didnt get it either poshuuuuuuuuuuuuuu expalin
or someone god dammit
where did u get this question from alooa???
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2 MINUTES..
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it says the R is parallel to (i-2j)
that means gradients will be equal.
how do we get the gradient from a coordinate
y/x right?
so whats the gradient for R vector
q-5/4+p
now m for (i-2j) note:- i is also equal to 1i which is 1
so the gradient for this will be, -2/1
equate the gradients
q-5/4+p = -2/1
so you get, q-5= -2(4+p)
yay i feel so smart! :D
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Her You Go..
Hope that helps..
:D
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thxxx alooot ;D ;D ;D
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any time ;)