AP Physics 1 · Summary

Unit 5 summary

1. Work in radians: one revolution is $2\pi$ rad. With constant $\alpha$, the linear motion equations carry over with $\theta$, $\omega$ and $\alpha$.
2. All points of a rigid object share $\omega$ and $\alpha$; a point at radius r has $v = r\omega$ and $a_t = r\alpha$.
3. Torque is $\tau = rF\sin\theta$, or force times lever arm; a force through the axis gives no torque. Give torques signs.
4. Rotational inertia grows with mass and, even more, with distance from the axis: $I = \sum mr^2$, measured from the chosen axis.
5. Static equilibrium needs zero net force and zero net torque; take torques about the point where an unknown force acts.
6. $\tau_{\text{net}} = I\alpha$. A pulley with mass needs different tensions on its two sides, and it makes the hanging masses accelerate less.