Optimizing River Crossing Time for a Hunter Using a Powerboat

In summary, the conversation discusses a hunter attempting to cross a river using a powerboat. The river is 1.5 km wide and flows at a speed of 5.0 km/h. The powerboat can move at a maximum speed of 12 km/h. The minimum time necessary for crossing is calculated by dividing the width of the river by the velocity of the hunter, which is found to be 13 km/h. This is due to the water moving upstream, resulting in a vector resultant of 13 km/h.
  • #1
joe215
26
0
1. Homework Statement

A hunter wishes to cross a river that is 1.5 km wide and flows with a speed of 5.0km/h parallel to its banks. the hunter uses a small powerboat that moves at a maximum speed of 12 km/h with respect to the water. What is the minimum time necessary for crossing?


3. The Attempt at a Solution

5km/h^2 + 12Km/h^2=sq rt 169km/h^2 = 13 km/h

The hunter moves really moves at 13 km/h to the right because of the water moving upstream. 13 is the vector resultant of 5 north and 12 east.

So, T=D/V

T=width of stream/velocity of hunter
T=1.5km/12km/h = 0.125 h
 
Physics news on Phys.org
  • #2
joe215 said:
1. Homework Statement

A hunter wishes to cross a river that is 1.5 km wide and flows with a speed of 5.0km/h parallel to its banks. the hunter uses a small powerboat that moves at a maximum speed of 12 km/h with respect to the water. What is the minimum time necessary for crossing?


3. The Attempt at a Solution

5km/h^2 + 12Km/h^2=sq rt 169km/h^2 = 13 km/h

The hunter moves really moves at 13 km/h to the right because of the water moving upstream. 13 is the vector resultant of 5 north and 12 east.

So, T=D/V

T=width of stream/velocity of hunter
T=1.5km/12km/h = 0.125 h

You calculate the correct velocity of the hunter (V = 13 km/h), but when you calculated his time of crossing you used V = 12 km/h.
 
  • #3
If I used 13km/h instead of 12km/h, would the answer be right?
 

1. How is quick 2d motion defined?

Quick 2d motion refers to the movement of an object in two dimensions at a fast rate. This means that the object is changing its position in both the horizontal and vertical directions simultaneously.

2. What factors affect quick 2d motion?

The factors that affect quick 2d motion include the initial velocity, acceleration, and the presence of external forces such as friction or air resistance.

3. How is quick 2d motion calculated?

Quick 2d motion can be calculated using the equations of motion, which take into account the initial velocity, acceleration, and time. It can also be calculated using vector analysis, which involves breaking down the motion into its horizontal and vertical components.

4. What is the difference between quick 2d motion and regular 2d motion?

The main difference between quick 2d motion and regular 2d motion is the speed at which the object is moving. Quick 2d motion involves high speeds and rapid changes in position, while regular 2d motion refers to slower and more uniform movements.

5. Can quick 2d motion be accurately predicted?

Yes, quick 2d motion can be accurately predicted using mathematical equations and principles such as Newton's laws of motion. However, external factors such as air resistance or friction can affect the accuracy of the predictions.

Similar threads

  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
10K
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
22
Views
4K
  • Introductory Physics Homework Help
Replies
13
Views
3K
  • Introductory Physics Homework Help
Replies
6
Views
7K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
3K
  • Introductory Physics Homework Help
Replies
2
Views
5K
Back
Top