emma31x12
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The horizontal unit vectors i and j are in the directions east and north respectively.

A model ship of mass 2kg is moving so that its acceleration vector ams^-2 at time t seconds is given by

a=3(2t-5)i+4j. When t=T, the magnitude of the horizontal force acting on the ship is 10N.

Find the possible values of T.

If someone could tell how to work through it that would be great because i have no idea where to start.
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Muttley79
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(Original post by emma31x12)
The horizontal unit vectors i and j are in the directions east and north respectively.

A model ship of mass 2kg is moving so that its acceleration vector ams^-2 at time t seconds is given by

a=3(2t-5)i+4j. When t=T, the magnitude of the horizontal force acting on the ship is 10N.

Find the possible values of T.

If someone could tell how to work through it that would be great because i have no idea where to start.
We cab't give you a solution as that is against the rules. Try using F = ma when t = T and post what you get.
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emma31x12
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(Original post by Muttley79)
We cab't give you a solution as that is against the rules. Try using F = ma when t = T and post what you get.
Oh i tried this before and i thought i was wrong: so i did
10= 2x(3(2t-5)i+4j)
10=12Ti-30i+8j
Am I completely off?😬
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profkerubo
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i can help you via email
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emma31x12
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(Original post by profkerubo)
i can help you via email
Thank you- I sent you a message w my email
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mqb2766
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(Original post by emma31x12)
Oh i tried this before and i thought i was wrong: so i did
10= 2x(3(2t-5)i+4j)
10=12Ti-30i+8j
Am I completely off?😬
use Pythagoras to find the magnitude of the corresponding force?
Equate to 10 and solve for T
Last edited by mqb2766; 1 month ago
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Muttley79
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(Original post by profkerubo)
i can help you via email
DOn't ask for e-mail or PM - help on here
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Muttley79
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(Original post by emma31x12)
Thank you- I sent you a message w my email
Please don't e-mail anyone on here - you have no idea who they are
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emma31x12
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(Original post by mqb2766)
use Pythagoras to find the magnitude of the corresponding force?
Equate to 10 and solve for T
Sorry, what do you mean by corresponding force? Do you mean that i should separate the vector given for acceleration into i and j?
Last edited by emma31x12; 1 month ago
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TheBrightSavage
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Newton's Second Law alongside some vector work (i and j)
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old_engineer
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(Original post by TheBrightSavage)
The Force given is the horizontal force not the total force so I think you solve it like this:
....
Please observe the posting guidelines (sticky): hints not full solutions. Please delete your solution.
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old_engineer
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(Original post by TheBrightSavage)
Could I PM him/her the solution?
That would hardly be in the spirit of the forum, would it?
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mqb2766
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(Original post by TheBrightSavage)
The Force given is the horizontal force not the total force so I think you solve it like this:
So you know the horizona ...
But it's wrong. Why not let the OP sort it out.
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mqb2766
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(Original post by emma31x12)
Sorry, what do you mean by corresponding force? Do you mean that i should separate the vector given for acceleration into i and j?
No. Get the magnitude of the acceleration (pythagoas) and multiply by 2 to get the (scalar) force, which is 10. It's easier to keep things squared up. Note that in your original reply, you set a scalar (10) equal to a vector (i+j) which doesn't really make sense.

Btw - if you change a response, it's better to do a new reply. Editing a previous one doesn't produce a notification.
Last edited by mqb2766; 1 month ago
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emma31x12
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(Original post by mqb2766)
No. Get the magnitude of the acceleration (pythagoas) and multiply by 2 to get the (scalar) force, which is 10. It's easier to keep things squared up. Note that in your original reply, you set a scalar (10) equal to a vector (i+j) which doesn't really make sense.

Btw - if you change a response, it's better to do a new reply. Editing a previous one doesn't produce a notification.
I see- Thank you and thanks for the tip !
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emma31x12
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(Original post by mqb2766)
No. Get the magnitude of the acceleration (pythagoas) and multiply by 2 to get the (scalar) force, which is 10. It's easier to keep things squared up. Note that in your original reply, you set a scalar (10) equal to a vector (i+j) which doesn't really make sense.

Btw - if you change a response, it's better to do a new reply. Editing a previous one doesn't produce a notification.
I got the answer- thank you soo much!
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