Finding the Width of a River Using Vector Properties

  • Thread starter Thread starter innightmare
  • Start date Start date
  • Tags Tags
    Properties Vectors
AI Thread Summary
To find the width of the river, the surveyor's method involves creating a right triangle using the baseline and the angle sighted to the tree. The problem is fundamentally a geometry/trigonometry issue rather than a vector problem, despite being presented in a vector chapter. Drawing a diagram can clarify the relationships between the sides and angles, making it easier to apply trigonometric functions. The width of the river can be calculated using the tangent of the angle and the length of the baseline. Understanding this approach simplifies the solution process significantly.
innightmare
Messages
35
Reaction score
0

Homework Statement



A surveyor measures the distance across a straight river by the following method:starting directly across from a tree on the opposite bank, she walks 100m along the riverbank to establish a baseline. Then she sights across a tree. The angle from her baseline to the tree is 35.0(degree). How wide is the river?

Homework Equations


I think this is a resultant vector problem. Where R(x)=A(x)+B(x), R(y)=A(y)+B(y). Then, Ill take the magnitude of both (R(x)+R(y))^1/2


The Attempt at a Solution



What I stated above is what I thought a solution, but I am stuck at the word "wide"? Not sure if I am on the right direction.
Thanks
 
Physics news on Phys.org
Sometimes drawing a picture helps out. Take a look at this one I sketched for you.

http://picasaweb.google.com/barry.farmer/Hw/photo?authkey=byWKUltIRn8#5110762258918870706
 
innightmare said:
I think this is a resultant vector problem.
This is geometry/trig problem, not a vector problem. Draw yourself a diagram and you'll find a right triangle.

Looks like lylos drew one for you!
 
Doc Al said:
This is geometry/trig problem, not a vector problem. Draw yourself a diagram and you'll find a right triangle.

Looks like lylos drew one for you!

So how can i even go about solving this problem, if its a right triangle formula? This homework question was in the vector chapter of the book
 
To solve many vector problems, you need to know about right triangles. This should be an easier problem than many vector ones.
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...

Similar threads

Replies
9
Views
7K
Replies
16
Views
3K
Replies
8
Views
10K
Replies
12
Views
3K
Replies
4
Views
2K
Back
Top