A ball is thrown straight upward and reaches the top of its path in 1.71 s (before it starts to come back down). A second ball is thrown at an angle of 34 degrees with the horizontal. At what speed must the second ball be thrown so that it reaches the same height as the one thrown vertically

Respuesta :

Answer:

The second ball must be thrown at 30.01 m/s.

Explanation:

First, we need to find the maximum height (H) reached by the ball 1:

[tex] v_{f_{1}}^{2} = v_{0_{1}}^{2} - 2gH [/tex]  

Where:

[tex]v_{f_{1}}[/tex]: is the final speed of ball 1 = 0 (at the maximum height)

[tex]v_{0_{1}}[/tex]: is the initial speed of ball 1        

g: is the gravity = 9.81 m/s²    

We need to find the initial speed, by using the following equation:

[tex] v_{f_{1}} = v_{0_{1}} - gt [/tex]

Where t is the time = 1.71 s (when it reaches the maximum height)

[tex] v_{0_{1}} = gt = 9.81 m/s^{2}*1.71 s = 16.78 m/s [/tex]

So, the maximum height is:                  

[tex] H = \frac{v_{0_{1}}^{2}}{2g} = \frac{(16.78 m/s)^{2}}{2*9.81 m/s^{2}} = 14.35 m [/tex]  

Finally, the speed at which ball 2 must be thrown is:

[tex]v_{f_{2y}}^{2} = (v_{0_{2y}}sin(\theta)})^{2} - 2gH[/tex]      

[tex]v_{0_{2y}}= \frac{\sqrt{2gH}}{sin(\theta)} = \frac{\sqrt{2*9.81 m/s^{2}*14.35 m}}{sin(34)} = 30.01 m/s[/tex]                    

                   

Therefore, the second ball must be thrown at 30.01 m/s.

I hope it helps you!