To throw a discus, the thrower holds it with a fully out-stretched arm. Starting from rest, he begins to turn with a con-stant angular acceleration, releasing the discus after making one complete revolution. The diameter of the circle in which the discus moves is about 1.8 m. If the thrower takes 1.0 s to complete one revolution, starting from rest, what will be the speed of the discus at release?

Respuesta :

Answer:

11.3m/s

Explanation:

We can find the solution through the rotational motion of the discus,

[tex]\theta = w_it+\frac{1}{2}\alpha t^2[/tex]

Where,

[tex]\theta = 2\pi[/tex]

[tex]w_i=0[/tex]

[tex]t=1s[/tex]

Solving to find [tex]\alpha[/tex],

[tex]2\pi = (0)(1)+\frac{1}{2}\alpha (1)^2[/tex]

[tex]\alpha = \frac{2\pi}{0.5}[/tex]

[tex]\alpha = 12.6 rad/s^2[/tex]

Therefore we can find the final angular velocity, through the rotational motion equation given by,

[tex]w_f = w_i + \alpha t[/tex]

Substituting,

[tex]w_f = 0 + 12.6*(1)[/tex]

[tex]w_f =12.6rad/s[/tex]

The diameter of the circle is 1.8m, then the ratio will be the half, i.e,

[tex]r=0.9m[/tex]

The relation between linear velocity and angular velocity is

[tex]v=rw_f[/tex]

[tex]v=(0.9)(12.6)[/tex]

[tex]v=11.3m/s[/tex]