hayley26
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Hi ! I got this question for a homework and I am reallyyyy stumped. I was hoping someone could guide me through where to even begin?:In this question the horizontal unit vectors i and j are in the directions east and north respectively.A model ship of mass 2 kg is moving so that its acceleration vector a ms^-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 10 N.Find the possible values of T.(4 marks)I have been given a clue to use pythagoras to find the magnitude of the corresponding force and equate to 10 to solve for T, but I dont understand that. Please help me :/
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chinjyanson
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Well picture what the scenario is and you will notice that the three things given to you is Force, mass and the vector of acceleration. So my first instinct is to use F=ma. I know my F to be 10 and I know my mass to be 2. So now I have 10=2a. Now how do I find my a? Well I have the acceleration in the i component, and I have the acceleration in the j component. Here we use the Pythagoras theorem to calculate our resultant vector for acceleration which equals to root((3(3t-5)^2)+(4^2)). Equate this to the 10=2a part and you have an equation to find T. This should be enough to finish the question off, but if you still dont understand it just @ me and I'll try to explain it in a different way
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davros
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(Original post by chinjyanson)
Well picture what the scenario is and you will notice that the three things given to you is Force, mass and the vector of acceleration. So my first instinct is to use F=ma. I know my F to be 10 and I know my mass to be 2. So now I have 10=2a. Now how do I find my a? Well I have the acceleration in the i component, and I have the acceleration in the j component. Here we use the Pythagoras theorem to calculate our resultant vector for acceleration which equals to root((3(3t-5)^2)+(4^2)). Equate this to the 10=2a part and you have an equation to find T. This should be enough to finish the question off, but if you still dont understand it just @ me and I'll try to explain it in a different way
Please keep hints to a minimum so the OP has a chance to do some working

Also it's not a good idea to offer help via pm as other users may be interested in this question too, so we try to include all the assistance in the original post. Thanks.
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hayley26
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Tysm! I solved it correctly from this! <33
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