A potter's wheel, with rotational inertia 46 kg · m2, is spinning freely at 40 rpm. The potter drops a lump of clay onto the wheel, where it sticks a distance 1.2 m from the rotational axis. If the subsequent angular speed of the wheel and clay is 32 rpm what is the mass of the clay?

Respuesta :

Answer:

mass of clay = 8 kg

Explanation:

Rotational inertia of wheel = [tex]I_{w}=46kg.m^{2}[/tex]

Angular speed of wheel =ω₁ = 40 rpm = 4.188 rad/sec

Clay drops on wheel from distance = r= 1.2 m

Angular speed of clay and wheel = ω₂ = 32 rpm = 3.35 rad/sec

To find:

Mass of clay = M =?

Angular momentum before clay drop = [tex]L_{1}=I_{w} \omega[/tex]

                                           [tex]L_{1}=(46)(4.188)[/tex]

                                           [tex]L_{1}=192.648kg.m^{2}/sec[/tex]

After collision, angular momentum =  [tex]L_{2}=I_{c+w} \omega_{2}[/tex]

Using concept of conservation of angular momentum

                                             L₁ = L₂

                                       [tex]192.648=I_{c+w} \omega_{2}[/tex]

                                       [tex]I_{c+w} =\farc{192.648}{3.35}[/tex]

                                       [tex]I_{c+w} =\farc{192.648}{3.35}[/tex]

                                       [tex]I_{c+w} =57.50 kg.m^{2}[/tex]

                                       [tex]I_{c+w} = I_{c}+I_{w}[/tex]

                                       [tex] I_{c}=I_{c+w}-I_{w}[/tex]

                                       [tex] I_{c}=57.50-46[/tex]

                                       [tex] I_{c}=11.50[/tex]

                                       [tex] I_{c}=m.r^{2}[/tex]

                                       [tex]m=\frac{I_{c}}{r^{2}}[/tex]

                                       [tex]m=8 kg[/tex]

The angular momentum of the body before the collision is always equal to the angular momentum of the body after the collision. The mass of the clay will be 8 kg.

What is the law of conservation of angular momentum?

According to the law of conservation of angular momentum, the angular momentum of the body before the collision is always equal to the angular momentum of the body after the collision.

The angular momentum of the body is given by the product of the mass and velocity of the body.

Angular momentum before clay drop = L₁= Iω = 46×4.188= 192.648 kgm²/sec.

The given data in the problem is ;

I is the rotational inertia of wheel =

ω is the  angular speed of wheel= 40 rpm = 4.188 rad/sec

r is the distance from the clay drops on the wheel 1.2 m

ω₂ is the angular speed of clay and wheel =  32 rpm = 3.35 rad/sec

M is the mass of clay=?

According to the law of conservation of angular momentum

Angular Momentum before clay drop =Momentum after clay drop

[tex]\rm L_1= L_2 \\\\ 192.648 = I_{C+\omega} \omega_2 \\\\ I_{C+\omega} =192.6483 \\\\ I_{C+\omega}=57.50 Kgm^2 \\\\ I_{C+\omega} = I_C+ I_\omega \\\\ I_c= i{c+ \omega}- I_{\omega} \\\\ I_c = 57.50 -4.6 \\\\ I_c= 11.50 \\\\ I_C= mr^2 \\\\ m = 8 Kg[/tex]

Hence the mass of the clay will be 8 kg.

To learn more about the angular momentum refer to the link;

https://brainly.com/question/1113396