This is a sneaky trick question, to help you discover whether you know
one of the differences between velocity and speed.
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If you make a list of the distances and directions, and ignore the times,
you find these:
4 - west, (3 + 1) - east . . . . . zero in the east/west direction
1.5 - north, 1.5 - south . . . . . zero in the north/south direction
This jogger went out, had a nice jog around the neighborhood,and ended up exactly where he started.
Average velocity = (distance between start point and end point) / (time)
IF the question asked for average SPEED, then you would need the total distance, and divide it by the total time. But it asks for VELOCITY, and <u>that</u> only involves the straight distance between the start point and the end point, regardless of the route taken in between.
The jogger ended up exactly where he started. The distance between start and end points was zero. Average velocity is (zero) / (time) . And that fraction is going to be <em><u>Zero</u></em>, no matter how long or how short the trip was, and no matter how much time it took.
Where Gravity rely's on only mass and distance and nothing else, so the weight on the planets will vary like you have stated. However Mars is smaller than Mercury, so the weight on Mars will be less, and the weight on Mercury will be more. Think this way.
More Mass = More Gravity = More Weight
Less Mass = Less Gravity = Less Weight