Chapter 7 - Circular Motion and Gravitation - Learning Path Questions and Exercises - Exercises - Page 263: 49

a). $1.8rad/s^{2}$ b). $28.7$

$\omega_{0}=250rpm=26.2rad/s$ $\omega=350rpm=36.6rad/s$ $\Delta t=5.75s$ a). angular acceleration $=\frac{\omega-\omega_{0}}{\Delta t}=\frac{10.4}{5.75}=1.8rad/s^{2}$ b). $\Delta\theta=\frac{\omega_{0}^{2}-\omega^{2}}{2a}=180rad$ Thus, number of revolutions =$\frac{180}{2pi}=28.7$