To calculate the velocity of a body, we use the formula:
velocity = distance / time
In this case, the distance traveled is 300 mm, and the time taken is 30 seconds. However, we need to ensure that the units are consistent. Let's convert the distance to meters:
300 mm = 300 / 1000 = 0.3 meters
Now we can calculate the velocity:
velocity = 0.3 meters / 30 seconds velocity = 0.01 meters per second
Therefore, the velocity of the body when it travels 300 mm in 30 seconds is 0.01 meters per second.