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Finding Mechanics question hard

Three forces of sizes 15 N, 7 N and 19 N pulling at 120° to each other are acting on a particle
Find:
a) The size of the resultant force
b) The direction of the resultant force to the 19N force
Convert each force into a vector (of lengths 19, 7 and 15, but bearings 0, 120,240 degrees), then add the vectors to get the resultant vector.
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alfiethfc02
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Original post by DFranklin
Convert each force into a vector (of lengths 19, 7 and 15, but bearings 0, 120,240 degrees), then add the vectors to get the resultant vector.

Thanks for replying so soon.

I'm finding it difficult to understand without drawing a diagram, but I can't do that either. So which vectors do you add?
Original post by alfiethfc02
Three forces of sizes 15 N, 7 N and 19 N pulling at 120° to each other are acting on a particle
Find:
a) The size of the resultant force
b) The direction of the resultant force to the 19N force

Draw a diagram - have you been taught how to resolve forces?
Original post by DFranklin
Convert each force into a vector (of lengths 19, 7 and 15, but bearings 0, 120,240 degrees), then add the vectors to get the resultant vector.

Unlikely to have been taught this yet ...
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alfiethfc02
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Original post by Muttley79
Draw a diagram - have you been taught how to resolve forces?

We have, but I'm unsure as to which direction you resolve.
Original post by alfiethfc02
We have, but I'm unsure as to which direction you resolve.

So pick one force to act up the paper say 19N, then draw a line 120 to that (15N) then the third at 240 to the first (7N) [I picked 19N to go up the page because of the second part]

Now an equivalent system will be a force P acting on a bearing theta.

Resolve vert for the three forces and put equal to Pcos theta

Repeat horiz and put equal to .... [have a guess]
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alfiethfc02
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Original post by Muttley79
So pick one force to act up the paper say 19N, then draw a line 120 to that (15N) then the third at 240 to the first (7N) [I picked 19N to go up the page because of the second part]

Now an equivalent system will be a force P acting on a bearing theta.

Resolve vert for the three forces and put equal to Pcos theta

Repeat horiz and put equal to .... [have a guess]

I got 5.1N and 40 degrees...but apparently this is wrong. Could anybody please explain?
Original post by alfiethfc02
I got 5.1N and 40 degrees...but apparently this is wrong. Could anybody please explain?

Post your working - we can't do questions for you.

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