# Physics

Two wheels have the same mass and radius of 4.0 kg and 0.35 m, respectively. One has (a) the shape of a hoop and the other (b) the shape of a solid disk. The wheels start from rest and have a constant angular acceleration with respect to a rotational axis that is perpendicular to the plane of the wheel at its center. Each turns through an angle of 13 rad in 8.0 s. Find the net external torque that acts on each wheel.

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1. They start standing still and accelerate to turn 13.0 rad in 8.0 seconds.

The average angular velocity during that interval is 13/8 = 1.625 rad/s. The maximum velocity achieved is twice that, 3.25 rad/s. The angular acceleraqtion rate is 3.25/8 = 0.4063 rad/s^2.

The torque is the angular acceleration rate divided by the moment of inertia, I. For the hoop, I = M R^2. For the disc, I = (1/2)MR^2.

The two wheels have different moments of inertia.

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2. Thank You!!!!!!

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3. An inverted “V” is made of uniform boards and weighs 373 N. Each side has the same length and makes a 30.0° angle with the vertical, as the figure shows. Find the magnitude of the static frictional force that acts on the lower end of each leg of the “V.”

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