The rotational inertia of a uniform thin rod about its end is ML2/3, where M is the mass and L is the length. Such a rod is hung vertically from one end and set into small amplitude oscillation. If L = 1.0 m this rod will have the same period as a simple pendulum of length:

Respuesta :

Answer:

0.67m

Explanation:

∑τ= Iα = - (L/2) mgsin(Θ)

(The net torque equals the negative horizontal component of gravity at the center of mass)(it's negative because the force is oppose of displacement)

sin(Θ) ≈ Θ , at small angles

α (1/3ML^2) = - (L/2) mg θ

2nd order differential equation

Θ = Asin(ωt)

^take the derivative twice

α = -Aω^2sin(ωt) = -θω^2

Go back to α (1/3ML^2) = - (L/2)mg θ

(-θω^2)(1/3ML^2) = - (L/2)mgθ

Cancel stuff out and solve for ω

[tex]Frequency=\sqrt{\frac{3g}{2l} }\\Period = 2(pi)\sqrt{\frac{3g}{2l} }=2(pi)\sqrt{\frac{3}{2} }\sqrt{\frac{g}{l} }[/tex]

ω [tex]=\sqrt{\frac{3g}{2l} }[/tex]

T = [tex]2\pi \sqrt{\frac{2l}{3g} }[/tex]

Plug in L = 1.0m

T = 1.639sec.

Simple Pendulum:

[tex]Period=2(pi)\sqrt{\frac{l}{g} }[/tex]

1.639 = [tex]2\pi\sqrt{\frac{l}{g} }[/tex]

L = 0.67m

The simple pendulum has a length of 0.67 m

For a physical pendulum, the period (T) is:

[tex]T=2\pi\sqrt{\frac{I}{mgh} }[/tex]

I = rotational inertia = ML²/3, L = 1 m, h = L/2 = 1/2

For a simple pendulum, the period (T) is:

[tex]T=2\pi\sqrt{\frac{L_o}{g} }[/tex]

I = rotational inertia = ML²/3, L = 1 m,

T = T, hence:

[tex]2\pi\sqrt{\frac{I}{mgh} }=2\pi\sqrt{\frac{L_o}{g} }\\\\{\frac{I}{mgh}} ={\frac{L_o}{g} }\\\\{\frac{I}{mh}} =L_o\\\\\\\frac{mL^2/3}{m(L/2)}=L_o\\\\ L_o=\frac{2L}{3}=\frac{2*1}{3} =0.67[/tex]

The simple pendulum has a length of 0.67 m

Find out more at: https://brainly.com/question/12886217