John walks to school in the morning then walks home for lunch. the school is 250 meters directly north of his house. after lunch, he goes back to school and then to a friend's house that is 550 meters south of the school. what is john's resultant displacement when he remains at his friend's house?

300 meters south
800 meters south
300 meters north
800 meters north

300 meters south

Explanation:

Displacement is a vector that connects the initial position with the final position of the motion.

In order to find the net displacement, we must add the distance covered in each part of the motion, considering the proper sign. We take the following convention:

North --> +

South --> -

So, John made the following trips:

Home --> school: 250 m north = +250

School --> home: 250 m south = -250

Home --> school: 250 m north = +250 m

School --> friend's house: 550 m south = -550 m

So, the net displacement is

d = +250 -250 +250 -550 = -300

So, 300 m south.

the answer is b, have negligible mass

does anyone know or what?