Why are volcanoes on mars taller than those on earth?

1. Lower gravity allows volcanoes to grow higher if you have them. 2. Mars is large enough to have had volcanoes in its past (though it does not have active volcanoes now). 3. Weathering is very low on Mars, so large volcanoes stay large. 4. Mars probablly didnt have any (or much) plate tectonics in its past. This means that heat from the interior had only a few places to escape from (hot spots) rather than all sorts of places to leak out (like the Ring of Fire).

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.