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Classical Mechanics

Moment of Inertia

Rotational Form of Newton's Second Law


I assume that you work through these problems using some sort of writing utensil. Take your pen, balance it on its tip, and let go. It falls over. How fast in m/s is the other end of the pen going when it hits the table, assuming the tip doesn't slip? Take the pen to be a uniform one dimensional rod of length 15 cm.

If an angular acceleration of \(28.0\text{ rad/s}^2\) is generated by a \(44.0\text{ N}\cdot\text{m}\) torque on a wheel, then what is the wheel's approximate rotational inertia?

Consider a diver who is launching from a diving board. When he launches from the board, his angular speed about his center of mass is changing from \(0\) to \(5.35\text{ rad/s}\) in \(190\text{ ms}.\) If the rotational inertia about his center of mass is \(12.0\text{ kg}\cdot\text{m}^2,\) what is the magnitude of average external torque on him from the board during the launch?

A cylinder is pinned at its center and two forces \(F_1=110\text{ N}\) and \(F_2=70\text{ N}\) are acting on it, as shown above. If the mass of the cylinder is \(100\text{ kg},\) what is the rotational acceleration produced by the two forces?

Two blocks of masses \(m_1=430\text{ g}\) and \(m_2=500\text{ g}\) are hanging on a pulley, as shown in the above figure. The pulley is fixed on a horizontal axle with negligible friction, and its radius is \(R=5.00\text{ cm}.\) If they are released from rest, block \(m_2\) falls \(48.0\text{ cm}\) in \(4.00\text{ s}.\) If there is no slippage between the cord and the pulley, what is the rotational inertia of the pulley?

The gravitational acceleration is \(g=9.8\text{ m/s}^2.\)


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