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Mechanics vector help

Any help would be appreciated
Reply 1
Original post by FaZe Temperrr
Any help would be appreciated

Help with what? You've posted a lot of questions there.

Please choose a part and show us your working and thoughts / explain why you're stuck.
Original post by notnek
Help with what? You've posted a lot of questions there.

Please choose a part and show us your working and thoughts / explain why you're stuck.


I'm struggling with all of it to be honest.

Thanks
Original post by notnek
Help with what? You've posted a lot of questions there.

Please choose a part and show us your working and thoughts / explain why you're stuck.


help with question 3 particularly would be great. Thanks
Reply 4
Original post by FaZe Temperrr
help with question 3 particularly would be great. Thanks

The boat is north of the buoy when both position vectors have the same i component (draw a diagram if this isn't clear).

Does this help?
Original post by notnek
The boat is north of the buoy when both position vectors have the same i component (draw a diagram if this isn't clear).

Does this help?


so would it be...

1+3t=7
3t=6
t=2

thanks
Reply 6
Original post by FaZe Temperrr
so would it be...

1+3t=7
3t=6
t=2

thanks

Yes that's correct.
Original post by notnek
Yes that's correct.


okay thanks for your help. For the b and c parts which components would be the same? Thanks
Original post by notnek
Yes that's correct.


Would you mind giving me some help on Q3 b and c, and Q4 d. Would really appreciate it. Thanks
Reply 9
Original post by FaZe Temperrr
Would you mind giving me some help on Q3 b and c, and Q4 d. Would really appreciate it. Thanks

I think you can do 3b yourself. Draw a diagram with one vector east of another - what can you say about their components? The thinking is similar to part a.

3c is harder but a diagram will help. You need a diagram with the origin and the position vector of the sandbank. Then show on your diagram where the boat could lie if the sandbank is north-west of it.

You need to use your diagram to work out the vector that goes from the boat to the sandbank. This vector is in the north-west direction so must have the form -ki + kj.

If you're stuck then this is going to be tough to explain on an internet forum. It would helo if you post any diagram that you're drawn.
Original post by notnek
I think you can do 3b yourself. Draw a diagram with one vector east of another - what can you say about their components? The thinking is similar to part a.

3c is harder but a diagram will help. You need a diagram with the origin and the position vector of the sandbank. Then show on your diagram where the boat could lie if the sandbank is north-west of it.

You need to use your diagram to work out the vector that goes from the boat to the sandbank. This vector is in the north-west direction so must have the form -ki + kj.

If you're stuck then this is going to be tough to explain on an internet forum. It would helo if you post any diagram that you're drawn.


Okay thanks, I think I have managed to do that. Any tips for question 4 part d? Thanks
Reply 11
Original post by FaZe Temperrr
Okay thanks, I think I have managed to do that. Any tips for question 4 part d? Thanks

Can you please post your answer for 4c?
IMG_20170212_214840.jpg
Original post by notnek
Can you please post your answer for 4c?


Not sure if its correct or not
Reply 13
Original post by FaZe Temperrr
IMG_20170212_214840.jpg

Not sure if its correct or not

Yes that's correct for the position vector of the boat.

If the boat is to collide with the lighthouse, there will be a time when the position vector of the boat is equal to 25i+23j.To find the this time you can set the i component of the boat equal to 25. Then verify that the time you get gives you a j component of 23.
Original post by notnek
Yes that's correct for the position vector of the boat.

If the boat is to collide with the lighthouse, there will be a time when the position vector of the boat is equal to 25i+23j.To find the this time you can set the i component of the boat equal to 25. Then verify that the time you get gives you a j component of 23.


Okay cheers mate, really appreciate your help :smile:

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