Question

A uniform rod pivoted at upper end is released when it is making an angle of 60^o. Find the radial force acting on a particle of mass dm at its tip when it makes an angle of 37⁰ with the vertical.

• A. 0.6 dm g
• B. 0.8 dm g
• C. 0.9 dm g
• D. None

Answer 1

Answer: (C)

0.9 dm g

Answer 2

$\frac{1}{2}$Iω² = mg $\frac{l}{2}$ (cos 37 – cos 60)

or $\frac{Ml^{2}}{3}$ω² = mgl(.8 - 5)

$\frac{mv^{2}}{l} = 0.9mg ⥂ ⥂ or\frac{v^{2}}{l} = 0.9g$

F_rad = dm$\frac{v^{2}}{l}$ = 0.9 (dm)g