If a particle covers half a circle in a time 't', we can determine its velocity and speed using some basic principles of circular motion.
Let's assume the radius of the circle is 'r'. The distance covered by the particle in half a circle is equal to the circumference of half the circle, which is πr.
Velocity is defined as the rate of change of displacement with respect to time. In this case, the displacement of the particle is equal to the diameter of the circle, which is 2r. Therefore, the velocity of the particle is given by:
Velocity = Displacement / Time = (2r) / t
The speed of the particle is the magnitude of its velocity and is given by:
Speed = |Velocity| = |(2r) / t| = (2r) / t
So, the velocity of the particle is (2r) / t, and the speed of the particle is (2r) / t.