River and boat velocity problem

In summary, a boat with a constant velocity of 9.0 m/s due north relative to the water crosses a river flowing due east at 1.20 m/s. Using the Pythagorean theorem and tangent, the velocity of the boat relative to the shore is calculated to be 9.08 m/s at 82.406 degrees north of east. To determine how far downstream the boat has moved by the time it reaches the north shore, the width of the river (380m) needs to be taken into account. The time it takes for the boat to cross the river is not provided in the conversation.
  • #1
akbro93704
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Homework Statement



(1) A River flows due east at 1.20 m/s. A boat crosses the river from the south shore to the north shore by maintaining a constant velocity of 9.0 m/s due north relative to the water. I got the velocity of the boat relative to shore at 9.08 m/s at 82.406 degrees north of east. What about if the river is 380m wide, how far downstream has the boat moved by the time it reaches the north shore?

Homework Equations





The Attempt at a Solution


I got the velocity by setting up components and using the Pythagorean theorem and tangent. What do I do with the 380m to figure out how far downstream the boat has moved by the time it reaches north shore? thanks
 
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  • #2
How long does it take for the boat to cross the river?
 
  • #3


Based on the given information, we can use the formula d = rt to calculate the distance traveled by the boat downstream. The distance (d) is equal to the rate (r) multiplied by the time (t). In this case, the rate is the velocity of the boat relative to the shore, which is 9.08 m/s. The time can be calculated by dividing the width of the river (380m) by the velocity of the boat relative to the water (9 m/s), which gives us a time of approximately 42.22 seconds. Therefore, the distance traveled downstream by the boat is 9.08 m/s x 42.22 s = 383.55 m. This means that by the time the boat reaches the north shore, it would have traveled approximately 383.55 meters downstream.
 

1. What is the difference between river velocity and boat velocity?

River velocity refers to the speed at which the water in a river is flowing. Boat velocity, on the other hand, refers to the speed at which a boat is moving relative to the surrounding water.

2. How does the direction of the river affect boat velocity?

The direction of the river can have a significant impact on boat velocity. If the boat is moving in the same direction as the river, it will have a higher velocity compared to when it is moving against the river's flow. This is because the boat will be aided by the river's current in the first scenario and will have to overcome it in the second scenario.

3. How can we calculate the velocity of a boat in a river?

To calculate the velocity of a boat in a river, we need to know the speed of the river's current and the speed of the boat relative to the water. We can then use vector addition to determine the resulting velocity of the boat.

4. What factors can affect the velocity of a boat in a river?

There are several factors that can affect the velocity of a boat in a river, including the speed and direction of the river's current, the size and shape of the boat, and external forces such as wind and waves. The shape and angle of the boat's hull can also impact its velocity.

5. How can we use the velocity of a boat in a river for navigation purposes?

Knowing the velocity of a boat in a river can be helpful for navigation purposes. It can help determine the time and distance it will take to reach a specific destination, the best route to take, and the amount of fuel needed for the journey. It can also be used to adjust the boat's speed to avoid obstacles and to safely navigate through narrow or fast-moving sections of the river.

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