Avisitor is staying in a tent that is 11 kilometers west of the closest point on a shoreline to a coral reef. the coral reef is 3 kilometers due south of the shoreline. the visitor plans to travel from the tent to the coral reef by running and swimming. if the visitor runs at a rate of 7 kmph and swims at a rate of 2 kmph, how far should the visitor run to minimize the time it takes to reach the coral reef

Explanation:

Given:

distance of tent from the closest point on shore-line,

distance between shoreline point and coral reef,

As shown in the schematic by a green dashed line representing the shortest distance (say l) that the visitor runs towards the reef in order to swim a minimum distance which takes least time.

Now on reaching at the shore at this point the visitor will have to swim the least distance due east to reach coral reef.

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it