12. Rotational Kinematics

A car drives at a constant $15\mathrm{m}/\mathrm{s}$ along a curve on city street with a radius of $70\mathrm{m}$. What is the acceleration of the car?

The dwarf planet Ceres has a radius of $476\mathrm{km}$, a mass of $9.5\times {10}^{20}\mathrm{kg}$, and a free fall acceleration due to gravity of $0.28\mathrm{m}/{\mathrm{s}}^2$. What speed will a rock have if it is orbiting Ceres, right on the surface? Ceres has no atmosphere – so there are no issues with air resistance – but assume that there are no mountains or large boulders to impede the orbit.