Unformatted text preview: alculate the of a acceleration of the bob using
F = ma .
(b) plane. When the string is at
s in a verticalWhat is the torque exerted about the pivot point? an angle θ to the vertic
(c) Show that τ = Iα with a = Lα gives the same tangential acceleration as found
in Part (a).
t = ma t , calculate the tangential acceleration of the bob? (b) Wh
t t t xerted about the pivot point? (c) Show that ∑τ = Iα with a t = L
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Solution tangential(a) The pendulum is seen in foundtoin Part (a).
acceleration as the ﬁgure the
right. The only tangential force is the component of gravity along the rotation path, Problem The pendulumsin θ.
F = mg
acting on it are Fshown in just solve for the
Since
= ma , then we
acceleration,
diagram. Note that the
F
=
a=
string is radial, and msog sin θ.
(b) The torque just τ rF ,
ential force the distanceisfrom the=pivot where rSo, L is
on the ball. point. =
ewton’s 2nd law in τ bothsin θ.
= mgL
nd rotational The torqueto τfind. Since the str...
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 Spring '10
 collins
 Physics, Force, Mass, Work, Rotation, mg sin

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