For arbitrary constants $\alpha, \beta$, the differential equation representing the family of curves $y=$ $(\alpha x+\beta) e^x$ is

A particle experiences an acceleration $\vec{a}=\alpha \vec{v}$, where $\vec{v}$ is the velocity of the particle and $\alpha$ is a constant. If the distances traveled by the particle in the time intervals $t_2-t_1$ and $t_3-t_1$ are $S_{12}$ and $S_{13}$, respectively, which of the following relations is true?

A point mass $m$ attached to a massless string is undergoing circular motion in a vertical plane. The length of the string is $R$ and the acceleration due to gravity is $g$. If the minimum value of the tension in the string is 2 mg , the maximum speed of this circular motion of the point mass is

An object is released from rest from the inner edge of a hemispherical bowl, and it falls under gravity. The coefficient of kinetic friction between the object and the bowl is $\mu$. If the object covers an angular displacement $\theta$ with respect to the center of the hemisphere when it stops for the first time, which of the following expressions is correct?