physics
posted by PLEASE HELP! on .
A boat travels at 3.8 m/s and heads straight across a river 240 m wide. The river flows at 1.6 m/s. Find
A) The boat's resultant velocity.
B) How long it takes the boat to cross the river.
C) How far downstream the boat is when it reaches the other side.
Please help, i have about 12 of these problems that I understand NONE of.

The time it takes to get across is 240m divided by 3.8 m/s, which is 63.2 seconds. In that time the current has moved boat downstream by: 1.6 m times 63.2 seconds, or 101.1 meters. Then to get the resultant velocity, you need to add the velocity vectors. Use pythagorean theorem: resultant^2 = 3.8^2 + 1.6^2. The resultant velocity is 4.1 m/s. Does this make sense??

Lazy Laz