Question

Give one example of a motion ,where an object does not change its speed but its direction of motion changes continuously.

Answer 1

Uniform circular motion in which an object moves on the circular path with constant speed, but its direction keeps changing from its position to the center of the circular path.

Answer 2

One example of a motion, where an object does not change its speed but its direction of motion changes continuously is the "uniform circular motion".  

When an object is in a uniform circular motion. For example, the motion of the earth in its orbit, does not change its speed constantly but this rotation causes the direction odd the motion to keep changing continuously, causing it to face the direction of the sun and the moon.