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mechanics and vectors

a particle of 2kg is acted upon by a constant force of 10N in vector direction 3i-4j and 50N in direction 7i+24j
it also has weight acting downwards of 19.6N

how can i resolve this??? to find one force???
Original post by mickymouse1995
a particle of 2kg is acted upon by a constant force of 10N in vector direction 3i-4j and 50N in direction 7i+24j
it also has weight acting downwards of 19.6N

how can i resolve this??? to find one force???


What are3 the directions of i and j ?
i.e. horizontal or vertical, and are they in the same plane as the line of the weight, i.e. is it a 2-dimensional or 3-dimensionalk problem ?
In any case you can combine the first two forces using the parallelogram rule.
Original post by mickymouse1995

10N in vector direction 3i-4j


Your direction vector has a certain magnitude.

You need to scale this vector so that it's magnitude is the same as that of the acting force in that direction. This will then give you a vector representing the force.

Then vector addition as per normal.
Reply 3
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mickymouse1995
OP
thanks guys
so ive now worked out the forces in each of north and east directions (on the paper) and i have the accelerations and velocities. i have to find the position vector of the particle, the initial position is the origin...

the force to the north is 40n and to the east is 20n
acceleration to the north is 20ms^-2 and to the east is 10ms^-2
velocity to the north is -15ms^-2 and to the east is 36ms^-2

no idea how to get a position vector from this.. but ive worked out that the particle moves 10m to the north and 92m to the east..

thank you guys xxx
Original post by mickymouse1995
thanks guys
so ive now worked out the forces in each of north and east directions (on the paper) and i have the accelerations and velocities. i have to find the position vector of the particle, the initial position is the origin...

the force to the north is 40n and to the east is 20n
acceleration to the north is 20ms^-2 and to the east is 10ms^-2
velocity to the north is -15ms^-2 and to the east is 36ms^-2

no idea how to get a position vector from this.. but ive worked out that the particle moves 10m to the north and 92m to the east..

thank you guys xxx


I get the impression that there is some information missing there. Are those the initial velocities? Or after a certain time period? Which is? What's the starting position?


I can see how you've added the forces (though you've not included the weight), and got an acceleration - which I agree with, at least in the i,j directions.
Reply 5
Avatar for mickymouse1995
mickymouse1995
OP
You dont need weight, I've realized, as there isn't a specific plane...

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