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XwyhyX
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1. Homework Statement
A flywheel in the form of a uniform disk (I = ½ MR2) 5.0 ft in diameter, weighs 650 lb. What will be its angular acceleration if a net force of 225 ft-lb acts it upon? If the disk is rotating at 1200 rev/min, what torque is required to stop it in 30 minutes?
T=I[itex]\alpha[/itex]=Fr
I need help in the first question, because apparently I arrive with a different answer from the solution that my teacher gave me. I just wanted to know if I got it wrong or my teacher forgot something
So using the definition of torque, I solve for alpha which is
alpha = FR/I
Defining I in the equation gives
alpha = FR/(1/2)MR2
Since the given is weight, I still have to define mass in the equation
alpha = FR/(1/2)(W/g)R2
Substituting the values, I'll have
alpha = (225)(2.5)/(1/2)(650/9.8)(2.5)2
alpha = 2.71 rad/s2
The solution in my note was
alpha = 2g(Torque)/WR2
which results to 3.54rad/s2Am I missing something? Or is everything just right?
A flywheel in the form of a uniform disk (I = ½ MR2) 5.0 ft in diameter, weighs 650 lb. What will be its angular acceleration if a net force of 225 ft-lb acts it upon? If the disk is rotating at 1200 rev/min, what torque is required to stop it in 30 minutes?
Homework Equations
T=I[itex]\alpha[/itex]=Fr
The Attempt at a Solution
I need help in the first question, because apparently I arrive with a different answer from the solution that my teacher gave me. I just wanted to know if I got it wrong or my teacher forgot something
So using the definition of torque, I solve for alpha which is
alpha = FR/I
Defining I in the equation gives
alpha = FR/(1/2)MR2
Since the given is weight, I still have to define mass in the equation
alpha = FR/(1/2)(W/g)R2
Substituting the values, I'll have
alpha = (225)(2.5)/(1/2)(650/9.8)(2.5)2
alpha = 2.71 rad/s2
The solution in my note was
alpha = 2g(Torque)/WR2
which results to 3.54rad/s2Am I missing something? Or is everything just right?