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# M1 Vectors watch

1. At 2pm the coastguard spots a rowing dinghy 500m due South of his observation point. The dinghy has constant velocity(2+3

a)Find in terms of t, the position vector of the dinghy t seconds after 2pm
I got 2t+(-500+3t)

b)Find the distance of the dinghy from the observation point at 2:05pm

Help pls on part b no idea what to do talk me through what to do.
2. (Original post by thefatone)
At 2pm the coastguard spots a rowing dinghy 500m due South of his observation point. The dinghy has constant velocity(2+3

a)Find in terms of t, the position vector of the dinghy t seconds after 2pm
I got 2t+(-500+3t)

b)Find the distance of the dinghy from the observation point at 2:05pm

Help pls on part b no idea what to do talk me through what to do.
Draw a diagram and see if it becomes clearer then
3. (Original post by SeanFM)
Draw a diagram and see if it becomes clearer then
this has done

absolutely nothing for me i'm not seeing anything
4. (Original post by thefatone)
this has done

absolutely nothing for me i'm not seeing anything
What does your diagram look like?

Can you see any way of finding the distance between where the dinghy isand the observation point?
5. (Original post by SeanFM)
What does your diagram look like?

Can you see any way of finding the distance between where the dinghy isand the observation point?
6. (Original post by thefatone)
What lovely paper

You have fallen into a trap - look carefully at the units in the question and then the time it asks you where the dingy is in the question.

But with that diagram you can still work out the method of finding the distance between the position and the origin.

How do you find the distance between the origin and the position? (You can think of them as x and y co-ordinates if you like).

Hint:
Spoiler:
Show
The distance is represented by a line that you already have on your diagram.
7. (Original post by SeanFM)
What lovely paper

You have fallen into a trap - look carefully at the units in the question and then the time it asks you where the dingy is in the question.

But with that diagram you can still work out the method of finding the distance between the position and the origin.

How do you find the distance between the origin and the position? (You can think of them as x and y co-ordinates if you like).

Hint:
Spoiler:
Show
The distance is represented by a line that you already have on your diagram.
no idea, 100% clueless
8. (Original post by thefatone)
no idea, 100% clueless
Okay, let's look at an example. If you had the point (3,4) on a graph and I asked you to find the distance between that and the origin, how would you do it?

Hint:
Spoiler:
Show
You can say that the origin has co-ordinates (0,0) if that helps.
9. (Original post by SeanFM)
Okay, let's look at an example. If you had the point (3,4) on a graph and I asked you to find the distance between that and the origin, how would you do it?

Hint:
Spoiler:
Show
You can say that the origin has co-ordinates (0,0) if that helps.
pythagoras
10. (Original post by thefatone)
pythagoras
Correct so, how does that help with anything?
11. (Original post by SeanFM)
Correct so, how does that help with anything?
it doesn't
12. (Original post by thefatone)
it doesn't
There is not much more I can say without giving away the answer so I'll go over what I've said before:

1. Remember to look at the units in the question and correct your position vector at 2:05.

2. Try and find the distance between the position vector and the origin using ...
13. (Original post by SeanFM)
There is not much more I can say without giving away the answer so I'll go over what I've said before:

1. Remember to look at the units in the question and correct your position vector at 2:05.

2. Try and find the distance between the position vector and the origin using ...
where's the 90° angle?
14. (Original post by SeanFM)
There is not much more I can say without giving away the answer so I'll go over what I've said before:

1. Remember to look at the units in the question and correct your position vector at 2:05.

2. Try and find the distance between the position vector and the origin using ...
i don't understand the time aspect of things, do i count time in hours or seconds?
15. (Original post by thefatone)
where's the 90° angle?
Well, where is the 90 degree angle between (0,0) and (3,4)?

For your time question, look at the question and see if you can work it out.

(I am deliberately giving you as little as possible so you can work it out for yourself )
16. (Original post by SeanFM)
Well, where is the 90 degree angle between (0,0) and (3,4)?

For your time question, look at the question and see if you can work it out.

(I am deliberately giving you as little as possible so you can work it out for yourself )
between the x-axis and line parallel to the y-axis but i'm not seeing how this helps me do this question :/ i don't know if it's a right angled triangle.

no idea, it's literally a guess i have no idea what i count time as maybe 5? 0.5? 0.005? i really don't know
17. (Original post by thefatone)
between the x-axis and line parallel to the y-axis but i'm not seeing how this helps me do this question :/ i don't know if it's a right angled triangle.

no idea, it's literally a guess i have no idea what i count time as maybe 5? 0.5? 0.005? i really don't know
(3,4) means that from (0,0) you go 3 to the right and 4 up. So you can draw a line 3 units to the right then 4 units up from that point, and then a straight line from (0,0) to (3,4) and there is your right angled triangle. The straight line represents the distance between the two points.

I'll give you another hint for the time - 2:05 is 5 minutes after 2 o'clock, and your velocity vector is measured in metres per second.
18. (Original post by SeanFM)
(3,4) means that from (0,0) you go 3 to the right and 4 up. So you can draw a line 3 units to the right then 4 units up from that point, and then a straight line from (0,0) to (3,4) and there is your right angled triangle. The straight line represents the distance between the two points.

I'll give you another hint for the time - 2:05 is 5 minutes after 2 o'clock, and your velocity vector is measured in metres per second.
i see so the time t is 300 then? so i sub in 300 as t? .-.

sooooo

i get
600+400?
19. (Original post by thefatone)
i see so the time t is 300 then? so i sub in 300 as t? .-.

sooooo

i get
600+400?
Correct. (as long you understand why, if you don't just say )

Okay, you're almost there. What next?
20. (Original post by SeanFM)
Correct. (as long you understand why, if you don't just say )

Okay, you're almost there. What next?
good point what next? i have no idea we have distance... final distance, time, constant velocity so this means a=0

soooo i'm done? 600+400 is my final answer? no... pythagoras

so thanks a ton

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