Question #85b24

2 Answers
Sep 3, 2017

a) 5 meters


Start with the extremes, and work backwards.

Straight ahead (OK, may 1' turn) would be 23 + 14 = 37. Not one of the options.

Straight back (180' 'turn') would be 23 - 14 = 9, also not an option, but as a minimum displacement it also eliminates 5 meters as an option.

Therefore, all of the others (10, 15, 20, 25) are possible, depending on the turn angle. ONLY a) 5 meters is NOT possible of the choices.

Sep 27, 2017

a.) #5 meters# is the displacement that is not possible in this scenario.


Since none of the directions of motion are given, any answer except a.) is a possible outcome or the change in displacement.

The change in displacement would depend only on the angle at which the runner turns after running the first #23 m#.

For example if the runner turns #180^0# at the end of #23m# and runs back #14m#, his change in displacement will be #9m# in his original direction. So if he were to run the second leg at a slight angle off #180^0#, then #10m# is possible.

At the same time, #5m# is not possible because he did not run far enough back to be within #5m# of his starting point.

The rest of the choices are all possible because his longest possible distance is #23m+14m=37m# where he has turned #360^0# at the turn. Any shorter distance is then in the range.

There is an example of negative displacement here: