physics
posted by Ty on .
questions( there are 3 so I will # 13)
info: A 18.9 kg object is attached to a cord that is wrapped around a wheel of radius 10.7 cm. The acceleration of the object down the frictionless incline is measured to be .9 m/s2. Assume the axle of the wheel to be frictionless. The acceleration of gravity is 9.8 m/s2.
1.) Find the tension in the rope. Answer in units of N
2.) Find the moment of inertia of the wheel. Answer in units of kg*m2
3.) Find the angular speed of the wheel 1.77 sec after it begins rotating, starting from rest. Answer in units of rad/sec.
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so lost! Don't even know where to begin!!!

Start with the tension.
T= mgma
Then the moment of inertia...
Torque=I *angular acceleration
Force*radius= I * linear acceleration/rad
solve for I. 
Found the tension which wasgreat! Thanks.
but would the linear acceleration be .9 m/s2? 
never mind I figured it out.
ok so then, for the angular speed, would I sinply use wfinal ^2=winitial^2+2(angular acceleration)(distance)
?