You travel 10 m north and then stop for lunch and

continued another 30 m north. you then turn around and

travel 40 m south. what is your displacement?

Zero

Explanation:

Displacement is a vector connecting the initial position with the final position of motion of an object.

In this case, we have the following motion:

10 m north

30 m north

40 m south

If we take north as positive direction and south as negative direction, we can identify each motion using the following displacement vectors:

So, the total displacement is:

Which means that the final position of the motion corresponds to the initial position.

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.