# Help with simple vectors?

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• Mar 19th 2013, 01:44 AM
iamapineapple
Help with simple vectors?
I'm currently really lost for as how to do these:

For each, I need to find i) the resultant velocity, ii) distance travelled across the river and iii) time it takes to cross river

b) a boat moving at a velovity of 10km/h heads upstream. The river is flowing at a velocity of 6km/h in an Easterly direction. The river is 1.2 km wide. If the boat ends up directly across from where it started, find i) ii) and iii)
For i) I got 11.67 km/h but that isn't right :/

c) a boat moving at a velovity of 10km/h on a bearing of N20oE, heads across a river which is flowing at a velocity of 6km/h in an Easterly direction. The distance across the river is 1.2 km. Find i) ii) and iii)

d) A boat moving at a velocity of 12km/h heads upstream at a bearing of N27oW. The river is flowing at a velocity of 7 km/h in an Easterly direction. The riveri s 350m wide. Find i) ii) iii)
For this one, I tried to equate the i and j components and then find the magnitude of the resultant vector. That was wrong too :C

Any help would be reallyyyy appreciated, this is practice for a major test.
• Mar 19th 2013, 01:58 AM
iamapineapple
Re: Help with simple vectors?
I solved d)! :D Turns out I was using the right method but I mistakenly did not make the i component negative for the triangle with 12 km/h! :D
• Mar 19th 2013, 02:39 AM
iamapineapple
Re: Help with simple vectors?
I just need help with b please