WillP
Dec5-04, 09:31 PM
I'm stuck on this question, which seems like it should be fairly simple:
A uniform rod of length 1.15 m is attached to a frictionless pivot at one end. It is released from rest from an angle theta = 21.0° above the horizontal. Find the magnitude of the initial acceleration of the rod's CM.
theres a graphic of it here:
http://capaserv.physics.mun.ca/msuphysicslib/Graphics/Gtype20/prob28_1012rod.gif
ok so what I've done so far is:
Rmg(sinθ) = Iα
Rmg(sinθ) = (1/3)mL^2α
getting the expression I = (1/3)mL^2 from my text book for a uniform rod with a pivot at its end.
working that out I get:
(0.575)(9.8)(sin21) = (1/3)(1.15)^2 α
α = 4.58 rad/s
then converting α to a with:
a = Rα
a = (.575)(4.58)
a = 2.63 m/s^2
but apparently this isn't right.
can anyone help me out?
A uniform rod of length 1.15 m is attached to a frictionless pivot at one end. It is released from rest from an angle theta = 21.0° above the horizontal. Find the magnitude of the initial acceleration of the rod's CM.
theres a graphic of it here:
http://capaserv.physics.mun.ca/msuphysicslib/Graphics/Gtype20/prob28_1012rod.gif
ok so what I've done so far is:
Rmg(sinθ) = Iα
Rmg(sinθ) = (1/3)mL^2α
getting the expression I = (1/3)mL^2 from my text book for a uniform rod with a pivot at its end.
working that out I get:
(0.575)(9.8)(sin21) = (1/3)(1.15)^2 α
α = 4.58 rad/s
then converting α to a with:
a = Rα
a = (.575)(4.58)
a = 2.63 m/s^2
but apparently this isn't right.
can anyone help me out?