The body travels along a circular path with a radius of 70 m. After traveling half a revolution in 20 seconds, we can find the average velocity and average speed.
(i) Average velocity: Average velocity is the displacement divided by the time taken. Since the body has traveled half a revolution, it has covered a distance equal to the circumference of half a circle.
Circumference of a circle = 2 * π * radius
Circumference of half a circle = (1/2) * 2 * π * 70 m = 70π m
Average velocity = Displacement / Time = 70π m / 20 s = 3.5π m/s
(ii) Average speed: Average speed is the total distance traveled divided by the time taken. In this case, the total distance traveled is equal to the circumference of a full circle.
Circumference of a circle = 2 * π * radius = 2 * π * 70 m = 140π m
Average speed = Total distance / Time = 140π m / 20 s = 7π m/s
Therefore, the average velocity is 3.5π m/s and the average speed is 7π m/s.