A roofing tile slides down a roof and falls off the roof edge 10 m above the ground at a speed of 6 m/s. The roof makes an angle of 30 degrees to the horizontal. How far from the exit point on the roof does the tile land?

Respuesta :

Answer:

4.49m

Explanation:

The vertical and horizontal component of the tile velocity when it exit the roof are

[tex]v_v = vsin(\alpha) = 6sin(30^0) = 3 m/s[/tex]

[tex]v_h = vcos(\alpha) = 6cos(30^0) = 3.89 m/s[/tex]

Let g = 9.8 m/s2. We can use the following equation of motion for the vertical distance landing to calculate the time t it takes to land

[tex]s_v = v_vt + gt^2/2[/tex]

[tex]10 = 3t + 4.9t^2[/tex]

[tex]4.9t^2 + 3t - 10 = 0[/tex]

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

[tex]t= \frac{-3\pm \sqrt{(3)^2 - 4*(4.9)*(-10)}}{2*(4.9)}[/tex]

[tex]t= \frac{-3\pm14.32}{9.8}[/tex]

t = 1.15 or t = -1.77

Since t can only be positive we will pick t = 1.15

This is also the time it takes for the tile to travel horizontally, we can use this to calculate how far from the exit point on the roof that it lands

[tex]s_h = v_ht = 3.89*1.15 = 4.49 m[/tex]