A fly-fishing line is cast in a parabolic motion with an initial velocity of 30 meters per second at an angle of [tex]$60^{\circ}$[/tex] to the horizontal and an initial height of 1 meter. The following parametric equations represent the path of the end of the line:

[tex] x(t) = \left(30 \cos \left(60^{\circ}\right)\right) t [/tex]

[tex] y(t) = -9.8 t^2 + \left(30 \sin \left(60^{\circ}\right)\right) t + 1 [/tex]

Graph the parametric equations to complete the statements:

1. To the nearest meter, the line travels a horizontal distance of [tex]$\square$[/tex] meters.
2. To the nearest tenth of a second, the end of the line reaches its maximum height after [tex]$\square$[/tex] seconds.



Answer :

To solve the problem, let's break it down step-by-step:

1. Convert the Angle to Radians:
[tex]\[ \text{Angle in radians} = 60^{\circ} \times \frac{\pi}{180} = \frac{\pi}{3} \text{ radians} \][/tex]

2. Set Up the Parametric Equations:

The parametric equations given are:
[tex]\[ x(t) = (30 \cos(60^{\circ})) t \][/tex]
[tex]\[ y(t) = -9.8 t^2 + (30 \sin(60^{\circ})) t + 1 \][/tex]

3. Calculate the Time When the Line Hits the Ground:

This happens when [tex]\( y(t) = 0 \)[/tex]:
[tex]\[ -9.8 t^2 + (30 \sin(60^{\circ})) t + 1 = 0 \][/tex]

Using the quadratic formula [tex]\( t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \)[/tex], where:
[tex]\[ a = -9.8, \quad b = 30 \sin(60^{\circ}), \quad c = 1 \][/tex]
The discriminant is:
[tex]\[ b^2 - 4ac = (30 \sin(60^{\circ}))^2 - 4 \cdot (-9.8) \cdot 1 \][/tex]

4. Solve for the Positive Root to Find the Time [tex]\( t_{\text{ground}} \)[/tex]:

The positive value of [tex]\( t \)[/tex] when [tex]\( y(t) = 0 \)[/tex] gives us the time at which the line hits the ground. After solving, we find:
[tex]\[ t_{\text{ground}} = 5.2 \text{ seconds} \][/tex]

5. Calculate the Horizontal Distance:

Using the horizontal parametric equation:
[tex]\[ x(t) = (30 \cos(60^{\circ})) t_{\text{ground}} \][/tex]
Plug in the values to find the horizontal distance:
[tex]\[ x(t_{\text{ground}}) = (30 \cos(60^{\circ})) \times 5.2 \approx 40 \text{ meters} \][/tex]

6. Find the Time to Reach Maximum Height:

The time to reach maximum height is when the vertical velocity component reaches 0. This is given by:
[tex]\[ t_{\text{max\_height}} = \frac{30 \sin(60^{\circ})}{9.8} \approx 2.7 \text{ seconds} \][/tex]

Thus, based on these calculations:

- The line travels a horizontal distance of approximately 40 meters.
- The end of the line reaches its maximum height after approximately 2.7 seconds.

So, the completed statements will be:

To the nearest meter, the line travels a horizontal distance of 40 meters.
To the nearest tenth of a second, the end of the line reaches its maximum height after 2.7 seconds.