A 5.00-kg mass on the end of a light string rotates in a circular motion on a horizontal frictionless desk. The radius of the circle is 0.800 m. The string has a breaking strength of 50.0 N. What is the fastest rotational speed of the mass that will not break the string?

Respuesta :

Answer:

The fastest rotational speed of the mass is [tex]3.536s^{-1}[/tex].

Explanation:

Here the string's breaking strength of 50.0 N means that the centripetal force exerted on the 5.00kg mass cannot exceed 50.0N—if it does, the string would break.

Therefore, we demand that

[tex](1).\;\: \dfrac{mv^2}{R} = 50.0N[/tex]

where [tex]m = 5.00kg[/tex], [tex]R = 0.800m[/tex] is the radius of the circle (also the length of the string), and [tex]v[/tex] is the tangential velocity of the mass.

Now, the tangential velocity can be written in terms of the rotational speed [tex]\omega[/tex] as follows:

[tex](2).\;\: v = \omega R[/tex],

and putting that into equation (1) we get:

[tex]\dfrac{m(\omega R )^2}{R} = 50.0N[/tex]

[tex]m \omega^2 R = 50.0N[/tex],

and we solve for the rotational speed [tex]\omega[/tex] to get:

[tex]\omega = \sqrt{\dfrac{50N}{mR} }.[/tex]

Finally, we out in the numeral values and get;

[tex]\omega = \sqrt{\dfrac{50N}{(5.00kg)(0.800m)} }.[/tex]

[tex]\boxed{\omega = 3.536s^{-1}}[/tex]

which is the fastest rotational speed of the mass.