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May 5, 2016

# Homework Help: Calculus and vectors

Posted by Jake on Tuesday, March 20, 2012 at 3:52am.

Bob can swim at a rate of 5km/h. He is in a river that is flowing at a rate of 9 km/h.

a) if bob swims upstream, what is his relative velocity to the ground?

b)if bob swims downstream, what is his relative velocity to the ground?

c) Someone decides to help Bob out of the water with a rope. bob swims across the river (perpendicular to the flow of water) in the same direction he's being pulled. The rescuer is pulling at a rate of 3 km/h. What is Bob's relative velocity to the ground?
• Calculus and vectors - bobpursley, Tuesday, March 20, 2012 at 8:20am

a. what is 9-5?
b. what is 9+5?

c. draw the figure.
the perpendicular across is 5km/hr
the downstream is 9km/hr

Hmmmm. How can he swim in the same direction he is being pulled, if he is swimming at 5km/hr and the rope is pulling slower? So, I dont understand the situation. Maybe he is no longer swimming, but being pulled, but the problem says..bob swims ...