A worker on the roof of a house drops his hammer, which slides down the roof at a constant speed of 4 m/s. The roof makes an angle of 30 degree with the horizontal, and its lowest point is 10 m above the ground. What is the horizontal distance traveled by the hammer after it leaves the roof of the house and before it hits the ground? Use g 10 m/s2.

Respuesta :

Answer:

4.25m

Explanation:

The horizontal and vertical component of the velocity as it leaves the roof is

[tex]v_v = vsin30^0 = 4*0.5 = 2 m/s[/tex]

[tex]v_h = vcos30^0 = 4*0.866 = 3.64 m/s[/tex]

Neglect air resistance, then gravitational acceleration g = 10m/s2 is the only thing that affect the vertical motion of the hammer. We can use the following equation of motion to solve for the time t of dropping

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

where h = 10m is the distance of dropping before the hammer reaches the ground

[tex]10 = 2t + 5t^2[/tex]

[tex]5t^2 + 2t - 10 = 0[/tex]

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

[tex]t= \frac{-2\pm \sqrt{(2)^2 - 4*(5)*(-10)}}{2*(5)}[/tex]

[tex]t= \frac{-2\pm14.28}{10}[/tex]

t = 1.23 or t = -1.63

Since t can only be positive we will pick t = 1.23

t is also the time that it takes to travel horizontally at the constant rate of 3.64 m/s

So the horizontal distance traveled by the hammer is

3.64*1.23 = 4.25 m

The Horizontal distance travelled by the hammer is : 4.26 m

Given data :

Speed of hammer = 4 m/s

Angle made by roof with the horizontal = 30°

Minimum distance of roof from ground = 10 m

g = 10 m/s²

Determine the horizontal distance travelled by the hammer

Considering the y-direction ( vertical ) to determine the Time ( t )

s = ut + 1/2 at²

- 10 = -4sin30 t + 1/2 * 10t²

 10 = 2t + 5t²

5t² + 2t - 10 = 0  ----- ( 1 )

Resolve equation ( 1 )

therefore :

t = 1.228 sec

The Horizontal distance is calculated using this formula

4 (cos 30°) t = 4 * cos 30 * 1.228

                 = 4.26 m

Hence we can conclude that the Horizontal distance travelled by the hammer is : 4.26 m

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