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A cannon fires a cannonball forward at a velocity of 48.1 m/s horizontally. If the cannon is on a mounted wagon 1.5 m tall, how far would the cannonball travel before it lands on the ground? (Show all work)

Respuesta :

Answer: 473.640 m

Explanation:

This situation is related to projectile motion or parabolic motion, in which the travel of the cannonball has two components: x-component and y-component. Being their main equations as follows:

x-component:

[tex]x=V_{o}cos\theta t[/tex]   (1)

Where:

[tex]V_{o}=48.1 m/s[/tex] is the cannonball's initial velocity

[tex]\theta=0[/tex] because we are told the cannonball is shot horizontally

[tex]t[/tex] is the time since the cannonball is shot until it hits the ground

y-component:

[tex]y=y_{o}+V_{o}sin\theta t-\frac{gt^{2}}{2}[/tex]   (2)

Where:

[tex]y_{o}=1.5m[/tex]  is the initial height of the cannonball

[tex]y=0[/tex]  is the final height of the cannonball (when it finally hits the ground)

[tex]g=9.8m/s^{2}[/tex]  is the acceleration due gravity

We need to find how far (horizontally) the cannonball has traveled before landing. This means we need to find the maximum distance in the x-component, let's call it [tex]X_{max}[/tex] and this occurs when [tex]y=0[/tex].

So, firstly we will find the time with (2):

[tex]0=1.5 m+48. 1 m/s sin(0\°) t-(4.9 m/s^{2})t^2[/tex]   (3)

Rearranging the equation:

[tex]0=-(4.9 m/s^{2})t^2+48. 1 m/s sin(0\°) t+1.5 m[/tex]   (4)

[tex]-(4.9 m/s^{2})t^2+(48. 1 m/s)  t+1.5 m=0[/tex]   (5)

This is a quadratic equation (also called equation of the second degree) of the form [tex]at^{2}+bt+c=0[/tex], which can be solved with the following formula:

[tex]t=\frac{-b \pm \sqrt{b^{2}-4ac}}{2a}[/tex] (6)

Where:

[tex]a=-4.9 m/s^{2}[/tex]

[tex]b=48.1 m/s[/tex]

[tex]c=1.5 m[/tex]

Substituting the known values:

[tex]t=\frac{-48.1 \pm \sqrt{48.1^{2}-4(-4.9)(1.5)}}{2(-4.9)}[/tex] (7)

Solving (7) we find the positive result is:

[tex]t=9.847 s[/tex] (8)

Substituting this value in (1):

[tex]x=(48.1 m/s)cos(0\°) (9.847 s)[/tex]   (9)

[tex]x=473.640 m[/tex]  This is the horizontal distance the cannonball traveled before it landed on the ground.