Can a moving object have a constant speed but a changing velocity?

For a particle in uniform circular motion,the acceleration $\vec{a}$ at a point $P(R, \theta)$ on the circle of radius $R$ is (Here $\theta$ is measured from the $x$-axis):

In Uniform Circular Motion ($U$.$C$.$M$.),when the time interval $\delta t \rightarrow 0$,the angle between the change in velocity $(\delta v)$ and the linear velocity $(v)$ will be (in $^{\circ}$)

Two particles having mass $M$ and $m$ are moving in a circular path with radius $R$ and $r$ respectively. The time period for both the particles is same. The ratio of angular velocity of the first particle to the second particle will be

The angular speed of the minute hand of a clock in degrees per second is

The angle between velocity and acceleration of a particle describing uniform circular motion is (in $^{\circ}$)