# Finding the angle of projection and its speed in 2D Kinetics

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1. Jul 28, 2015

### dahano

1. The problem statement, all variables and given/known data: The trajectory of a projectile in a vertical plane is y = √3 x - (1/5)x2, where x and y are respectively horizontal and vertical distances of the projectile from the point of projection. Find the angle of projection and speed of projection.

2. Relevant equations: 2-Dimensional Equations and maybe calculus.

3. The attempt at a solution: Honestly, I can't even understand that how do I begin with this question. I've tried some wild attempts but they landed me no where :-( Can you please guide me with the solution to this question?

2. Jul 28, 2015

### Qwertywerty

Please post these attempts .

However I still give a hint :

What does dy/dx represent ?
What is the formula for Range ?

3. Jul 28, 2015

### andrevdh

The angle of projection can be found from the gradient of the graph at what point?

4. Jul 28, 2015

### dahano

I figured out the formula for Ran
I figured out the formula of range as: u2Sin2(theta)/g

Can you tell me that how would it be done further?

5. Jul 28, 2015

### dahano

Sorry to ask a stupid question but what do you mean by point? Can you please show me how would it be solved?

6. Jul 28, 2015

### Qwertywerty

Here - dy/dx at x = 0 represents tan(θ) ( where θ is angle of projection ) .

Find range , and then using formula for range find u .

Last edited: Jul 28, 2015
7. Jul 28, 2015

### andrevdh

What does the trajectory or path of the projectile look like?
What is the equation which describes the path or trajectory?

8. Jul 28, 2015

### Staff: Mentor

Please attach your working for this.

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