A punter wants to kick a football so that the football has a total flight time of 4.70s and lands 57.0m away (measured along the ground). Neglect drag and the initial height of the football.


- How long does the football need to rise?


- What height will the football reach?


- With what speed does the punter need to kick the football? (vertical component, horizontal component, and vector magnitude)


- At what angle (θ), with the horizontal, does the punter need to kick the football?

Respuesta :

The projectile launch relations allow finding the results for the different questions are:

     1. Rise time is 2.35 s

    2. The maximum height is 27 m

    3. The initial velocity is 26 m / s

    4. The launch angle is 62.3º

The launch of projectiles is an application of kinematics to the movement of objects near the earth's surface, in this case there is no acceleration on the x-axis and the acceleration is the gravity acceleration on the y-axis.

In the attachment we have a movement diagram of the football ball

1.  As the acceleration is constant, the time it takes the body to go up is equal to the time it takes to go down, therefore, as the total time affects, the time it takes to go up is half.

         [tex]t_u =\frac{t_{total} }{ 2}[/tex]  

          t_u = 4.70 / 2

          t_u = 2.35 s

2. How high does the ball reach?

At the point of maximum height the vertical velocity is zero

        [tex]v_y = v_{oy} - g t\\0= v_{oy} - gt\\v_{oy} = gt[/tex]

       [tex]v_{oy}[/tex] = 9.8 2.35

        [tex]v_{oy}[/tex] = 23 m / s

Now we can use the equation.

         [tex]v_y^2 = v_{oy}^2 - 2 g y\\0 = v_{oy}^2 - 2 g y\\\\y = \frac{v_{oy}^2}{2g}[/tex]

        y = [tex]\frac{23^2}{2 \ 9.8}[/tex]

        y = 27 m

2. What is the initial velocity?

The initial vertical velocity is 23 m / s

We look for the horizontal speed.

            [tex]v_x = \frac{x}{t}[/tex]

They indicate the throw range is 57 m in the time of 4.70 s

            vₓ = 57.0 / 4.70

            vₓ = 12.1 m / s

To calculate the magnitude we use the Pythagorean Theorem

            v₀ = [tex]\sqrt{v_{ox}^2 + v_{oy}^2}[/tex]  

            v₀ = [tex]\sqrt{12.1^2 + 23^2}[/tex]  

            v₀ = 26 m / s

3. The launch angle

Let's use trigonometry

          tan θ = [tex]\frac{v_{oy}}{v_{ox}}[/tex]  

          θ = tan⁻¹ [tex]\frac{v_{oy}}{ v_{ox}}[/tex]

          θ = tan⁻¹  [tex]\frac{23}{12.1}[/tex]

          θ = 62.3º

In conclusion, using the projectile launch relatios we can find the results for the different questions are:

     1. The rise time is 2.35 s

    2. The maximum height is 27 m

    3. The initial velocity is 26 m / s

    4. The launch angle is 62.3º

Learn more here: brainly.com/question/10903823

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