# Calculus and vectors

posted by .

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 -

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 don't understand the situation. Maybe he is no longer swimming, but being pulled, but the problem says..bob swims ...

## Similar Questions

1. ### physics

You want to swim straight across a river that is 76m wide. You find that you can do this if you swim 28 degrees upstream at a constant rate of 1.7m/s relative to water. At what rate does the river flow?
2. ### physics

A River Is Flowing at a velocity of 0.15 m/s west. a swimmer swims against the current at a velocity of 0.22 east, how manyu hours will it take him to swim 1 km?
3. ### Mechanics M1

A girl swims across a river. When she swims in still water, she swims at 1.25 m/s, the river flows parallel to its banks at v m/s. The girl aims to swim upstream at angle θ degree to the river bank so that her resultant velocity …
4. ### Math

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?
5. ### physics

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?
6. ### physics

Noah wants to swim across a river 10 m wide, flowing from north to south. He swims so his velocity with respect to the river is 2 m/s due east, and the river moves at 4 m/s. How far downstream in m from his starting point will he reach …
7. ### physics

Noah wants to swim across a river 10 m wide, flowing from north to south. He swims so his velocity with respect to the river is 2 m/s due east, and the river moves at 4 m/s. How far downstream in m from his starting point will he reach …
8. ### math

A man who can swim at 5km/h in still water swims towards the east to cross arriver. If the river flows from north to south at the rate of 3km/h a) Calculate: i) The resultant speed ii) The drift b) If the width of the river is 30m, …
9. ### science(physics)

The stream of a river is flowing with velocity 1 km/h.What should be the direction of a swimmer to cross the river straight if he can swim at the rate of 2 km/h in still water.
10. ### math

A girl swims across a river. When she swims in still water, she swims at 1.25 m/s, the river flows parallel to its banks at v m/s. The girl aims to swim upstream at angle θ degrees parallel to the river bank so that her resultant …

More Similar Questions