I proved a physics equation. Does any one know if theirs an equation like this?

  • Thread starter Ambrose 2014
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In summary, the conversation discusses the direction and velocity of a plane traveling to a small lake with a given wind velocity and air speed. The conversation includes a detailed explanation and mathematical proof of the equations used to calculate the direction and velocity of the plane. The formula for solving such problems is also discussed, along with alternative methods such as using circular slide rules.
  • #1
Ambrose 2014
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Direction of a plane proof
48. A pilot wants to land at a small lake that is [N30.0 ̊W] of the airport that she is starting from. The wind has a velocity of 25.0 m/s[W] and the air speed of the plane is 1.90 × 10^2 m/s . What direction will the plane have to fly to get to its destination? What will be the velocity of the plane relative to the ground?

vt as the speed you'll achieve .
x as the plane speed or velocity.
w as wind speed or velocity.
Θ as the angle the plane has to go to achieve angle Φ at vt speed.
Φ as the angle away from start.

Know start to take the big picture coloured in red
vt^2=(xsinΘ+w)^2+(xcosΘ)^2
vt^2=(x^2sinΘ^2+wxsinΘ+wxsinΘ+w^2)+(x^2cosΘ^2)

now we have to get rid of the cosΘ^2 by taking(in green)
x^2=(x^2sinΘ^2)+(x^2cosΘ^2)
With x^2 divided
x^2/x^2=(x^2sinΘ^2)/x^2+(x^2cosΘ^2)/x^2
1=sinΘ^2+cosΘ^2
1-cosΘ^2=sinΘ^2
Now sub into the red coloured equation

vt^2=x^2(1-cosΘ^2)+wxsinΘ+wxsinΘ+w^2)+(x^2cosΘ^2)
vt^2=(x^2-x^2cosΘ^2)+(wxsinΘ+wxsinΘ+w^2)+(x^2cosΘ^2)
vt^2=x^2+2wxsinΘ^2+w^2

Now look at what's coloured in blue which is used to get rid of vt
sinΦ=(xsinΘ+w)/vt
(vt=(xsinΘ+w)/sinΦ)^2
vt^2=(x^2sinΘ^2+wxsinΘ+wxsinΘ+w^2)/sinΦ^2

Now we sub this equation into the red and green equation

(x^2sinΘ^2+2wxsinΘ+w^2)/sinΦ^2=x^2+2wxsinΘ+w^2

Move everything over to left

(x^2sinΘ^2/sinΦ^2)+(2wxsinΘ/sinΦ^2-2wxsinΘ)
(+w^2sinΦ^2-x^2-w^2)=0
A B C
Use the quadratic formula
sinΘ=-(2wx/sinΦ^2-2wx)+/-square root((2wx/sinΦ^2-2wx)^2-4x^2/sinΦ^2(w^2/sinΦ^2-x^2-w^2)/2x^2/sinΦ^2

sinΘ=(-2wx/sinΦ^2+2wx)+/-square root((4x^2w^2/sinΦ^4-4w^2x^2/sinΦ^2-4w^2x^2/sinΦ^2+4w^x^2)(-4x^2w^2/sinΦ^4+4x^4/sinΦ^2+4w^2x^2/sinΦ^2))/2x^2/sinΦ^2

sinΘ=(-2wx/sinΦ^2+2wx)+/-square root((-4w^2x^2/sinΦ^2+4w^x^2+4x^4/sinΦ^2))/2x^2/sinΦ^2

sinΘ=(-2wx/sinΦ^2+2wx)+/-square root((-4w^2x^2+4x^4)/sinΦ^2+4w^2x^2)/2x^2/sinΦ^2

multiply the whole equation by sinΦ^2
sinΘ=(-2wx+2wxsinΦ^2)+/-square root((-4w^2x^2+4x^4)sinΦ^2+4w^2x^2sinΦ^4)/2x^2
divid the equation by 2

sinΘ=(-wx+wxsinΦ^2)+/-
square root((-w^2x^2+x^4)sinΦ^2+w^2x^2sinΦ^4)/x^2
Divid by x
sinΘ=(-w+wsinΦ^2)+/-square root((-w^2+x^2)sinΦ^2+w^2sinΦ^4)/x

now say + not +/- and factor out sinΦ out of what's in the
Square root since we don't want a negative angle.

sinΘ=(-w+wsinΦ^2)+square root((-w^2+x^2+w^2sinΦ^2))sinΦ/x
Also written as

sinΘ=square root((-w^2+x^2+w^2sinΦ^2))sinΦ+(-w+wsinΦ^2)/x
if wind is in y direction
cosΘ=square root((-w^2+x^2+w^2cosΦ^2))cosΦ+(-w+wcosΦ^2)/x

x>w
If wind is going to opposite your going make negative.
 
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  • #2
Just as an aside on your problem, addressing your terminology. You cannot "prove" anything in physics, only in math, so if you proved it, it's math. Physics is always subject to disproof, math not so much.
 
  • #3
Thank you for the advice I'm only in grade 11 and I didn't take physics yet
 
  • #4
Ambrose 2014 said:
Thank you for the advice I'm only in grade 11 and I didn't take physics yet

Well, welcome to the forum
 
  • #5
Hey thanks and this is my first time posting so that's why I didn't know what section to put my formula question in and by the way this is only for x direction the other one for cos I proved mathematically on paper but didn't type up yet.
 
  • #7
It maybe long but I did so I can create an equation to solve problems like this since I like using equation and wouldn't sin and cosine laws work too
 

1. What is the significance of proving a physics equation?

Proving a physics equation means that you have provided evidence and logical reasoning to support a specific relationship between physical quantities. It helps to validate existing theories and contributes to the advancement of scientific knowledge.

2. How do I know if my physics equation has already been proven?

You can search for existing literature and research on your equation to see if it has already been proven. You can also consult with other scientists in the field for their knowledge and insights.

3. Can I use my proven physics equation in real-world applications?

It depends on the context and the accuracy of your equation. If your equation is based on sound scientific principles and has been rigorously tested, it may have practical applications in fields such as engineering and technology.

4. What are the steps to proving a physics equation?

The process of proving a physics equation involves conducting experiments, collecting data, and analyzing the results. It also requires a thorough understanding of the underlying principles and theories related to the equation.

5. How can I share my proven physics equation with the scientific community?

You can publish your findings in scientific journals, present them at conferences and seminars, or collaborate with other scientists to further validate your equation. Sharing your work with the scientific community allows for peer review and contributes to the advancement of knowledge in the field.

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