A potter's wheel is rotating around a vertical axis through its center at a frequency of 2.0 rev/s. The wheel can be considered a uniform disk of mass 4.9 kg and diameter 0.40m. The potter then throws a 2.7 kg chucnk of clay, approximately shaped as a flat disk of radius 8.0 cm, onto the center of the rotating wheel.

What is the frequency of the wheel after the clay sticks to it? Ignore friction/.

Respuesta :

Answer:

[tex]\omega_f=12.2954 \,rad.s^{-1}[/tex]         i.e.

[tex]Frequency=1.9569\,rev.s^{-1}[/tex]

Explanation:

Given:

angular speed,[tex]\omega_i =2\times 2\pi \,rad.s^{-1}[/tex]

mass of the disk, [tex]M=4.9\,kg[/tex]

radius of the disk, [tex]R=0.2\,m[/tex]

mass of the chunk, [tex]m=2.7\,kg[/tex]

radius of the chunk, [tex]r=0.04\,m[/tex]

We know that the angular momentum is given by:

[tex]L=I.\omega[/tex]

and moment of inertia for a disc:

[tex]I=\frac{1}{2} m.r^2[/tex]

According to the conservation of angular momentum, the final angular momentum is equal to the initial angular momentum.

[tex]\frac{1}{2} \times M.R^2\times \omega= \frac{1}{2} \times (M.R^2+m.r^2) \omega_f[/tex]

[tex]4.9\times 0.2^2\times (2\times 2\pi)=(4.9\times 0.2^2+2.7\times 0.04^2 )\tiems \omega_f[/tex]

[tex]\omega_f=12.2954 \,rad.s^{-1}[/tex]

[tex]Frequency=1.9569\,rev.s^{-1}[/tex]