Physics problem!!! i'm confused?

G

glenn

New member
i can answer some problem about vectors, but this one is the one i want others help me...
given: d1=300N at 0 degrees d3= 400N at 30 degrees
d2= -400N at 150 degrees
find the resultant displacement
 
First of all, i think you mean resultant force, because it's impossible to find the resultant displacement. Second, every vector question works exactly the same way: break out the vector into it's x and y components and add em up.

d1)
x= 300
y= 0

d2)
x=-400 cos 150= 200 sqrt 3
y=-400 sin 150= -200

d3)
x=200 sqrt 3
y=200

add em up
x=400 sqrt 3 + 300
y=0

finding the resultant is easy, all is in the x-direction. the resultant force is therefore exactly 400 sqrt 3 +300 which is approximately 993 N at 0 degrees
 
You break down the vectors into unit-vector form:
d1 = 300N cos0 i + 300N sin 0 j
d2 = -400N cos150 i - 400N sin 150 j
d3 = 400N cos 30 i + 400 sin 30 j

Once you've converted them in i-j notation, all you have to do is add them up and you get the resultant displacement. If you need to convert it back in polar, use: tan (theta) = j / i to get the angle and a^2 + b^2 = c^2 to get the magnitude.

Hope this helps!
 
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