Kinematics Question -- A soccer ball bounces off a wall

[Dr. Octavius]

Homework Statement

"A person kicks a soccer ball at an angle 30° above the horizontal on the ground. The ball then hits a wall at an angle 15° below the horizontal 4.9 seconds later. Determine the height at which the ball hit the wall."

(Assume acceleration due to gravity is 9.80m/s² [Down].)

Homework Equations

Not entirely sure where to start, but perhaps cos A₁ = vx / vi and sin A₁ = viy / vi as well as cos A₂ = vx / vf and sin A₂ = vfy / vf.

The Attempt at a Solution

Use the above equations to find vx (?) by subbing them into one of the five kinematic equations. Then find viy and vfy using ratios. Lastly, use viy and vfy to determine the displacement at the max height and the displacement downwards from the max height to the wall. Find the difference of the two values to determine the answer to the question.

I feel like I might not be seeing something here. Anyone care to provide some sort of solution?

Thanks.

 

[Suraj M]

I hope you used the concept of constant horizontal velocity which will lead you to the ratio ##\frac{v_f}{v_i}##
Then from there by just substituting the answer into the equation for the y coordinate of the velocity, you can find displacement, use third equation.
Post your calculations(working), it'll be easier to say, if your on the right track or not!

 

[haruspex]

Be prepared to create additional variables so that you can write out the standard equations. In the present case, I would suggest setting s as the horizontal distance.
When you post your working, please keep everything symbolic, e.g. write g, not 9.8, and t, not 4.9.

 

[PeroK]

If you need a hint, think of trigonometry and in particular the tangent of an angle.