One end of a uniform rope of mass m and length L is attached to a shaft that is rotating at constant angular velocity of magnitude w. The other end is attached to a point-like object of mass m. Find, the tension F in the rope as a function of r, the distance from the shaft. You may ignore the effect of gravitation.

Respuesta :

Answer:

Explanation:

Tension in the rope will be due to pseudo -force ( centrifugal force )

Centrifugal force = m rω² where m is mass being rotated and r being distance from the axis and ω is angular velocity. Naturally it will be dependent on r,  distance from the axis.

For terminal mass m attached at the end , the value of this force

F = m  ω² L

For other parts . we shall have to integrate the  values along the length because the value of m x r varies along the length.

Calculate the value of tension for  a small fraction of length dr at distance r along the length .

Mass of the fraction dr = m/L X dr

Tension due to the fraction

dT = m/L  dr X ω² r

Integrating both sides and taking limit from Lto r

T =[tex]\frac{m}{L} \int\limits^L_r {r} \, dr[/tex]

= [tex]\frac{m}{2L}\times(L^2-r^2)[/tex]

Total tension

= F +T

= [tex]\frac{m}{2L}\times(L^2-r^2)[/tex] + m  ω² L

= [tex]\frac{m\omega^2}{2L} ( 3L^2-r^2)[/tex]

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