2. An archer shoots an arrow at 83.0 m/s at a 62.0 degree angle. If the ground is flat, how much time is the arrow in the air?

Respuesta :

Answer:

t=14.96 sec

Explanation:

Diagonal Launch

It's a physical event that happens where an object is thrown in free air (no friction) forming an angle with the horizontal reference. The object then describes a path called a parabola.

The object will reach its maximum height and then return to the height from which it was launched. The equation for the height is :

[tex]\displaystyle y=y_o+v_osin\theta \ t-\frac{gt^2}{2}[/tex]

Where vo is the initial speed, [tex]\theta[/tex] is the angle, t is the time and g is the acceleration of gravity .

In this problem we'll assume the arrow was launched from the ground level (won't consider the archer's height). Thus [tex]y_o=0[/tex], and:

[tex]\displaystyle y=v_osin\theta \ t-\frac{gt^2}{2}[/tex]

The value of y is zero twice: when t=0 (at launching time) and in t=[tex]t_f[/tex] when it goes back to the ground. We need to find that time [tex]t_f[/tex] by making [tex]y=0[/tex]

[tex]\displaystyle 0=v_osin\theta\ t_f-\frac{gt_f^2}{2}[/tex]

Dividing by [tex]t_f[/tex]

[tex]\displaystyle v_osin\theta=\frac{gt_f}{2}[/tex]

Then we find the total flight time as

[tex]\displaystyle t_f=\frac{2v_osin\theta}{g}[/tex]

[tex]\displaystyle t_f=\frac{2(83)sin\ 62^o}{9.8}[/tex]

[tex]\displaystyle t_f=14.96\ sec[/tex]