Homework Help: New to 11 Physics

1. Jul 3, 2011

myjackie

1. The problem statement, all variables and given/known data
1) A ferry boat is crossing a river that is 8.5 x 10^2m wide. The average velocity of the water relative to the shore is 3.8 m/s [E] and the average velocity of the boat relative to the water is 4.9 m/s .
a. Determine the velocity of the ferry boat relative to the shore.
b. How long does the crossing take?
c. Determine the displacement of the boat as it crosses from the north shore to the south shore.

I'm preparing for Physics 11 during the summer by having a tutor and I seem to have a lot of difficulty understanding anything... Does anyone mind walking me through this question?

2. Relevant equations
a=(Vf-Vi)/t
Vf=Vi+at
d=Vit+1/2a^2

3. The attempt at a solution

From what I know, I am only given the velocity of the water relative to the shore (3.8 m/s [E]) and the velocity of the boat relative to the water (4.9 m/s ). Is there a acceleration variable that I missed because I have no idea how to solve this problem with just the velocities.

Last edited: Jul 3, 2011
2. Jul 3, 2011

lewando

It is good that you are taking steps to prepare for your next class. This question probably came from a chapter in a physics textbook that discussed vectors. Have you learned about vectors?

3. Jul 3, 2011

myjackie

Oh yes, I did learn about vectors, but I'm struggling to understand that as well...

4. Jul 3, 2011

myjackie

Okay, I just read over my notes... Am I suppose to form a right angle triangle with the velocities and find the "resultant vector"?

5. Jul 3, 2011

lewando

Yes. Hopefully, your notes cover how to get the angle of the resultant vector. I would suggest drawing a graphical representation of the problem to help you retain your wits.

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