Three force vectors are added together. One has a magnitude of 9 N, the second one a magnitude of 18 N, and the third a magnitude of 15 N. What can we conclude about the magnitude of the net force vector? Explain. I. It must equal 42 N. II. It cannot be 0 N. III. Anything from –42 N to +42 N. IV. It can be anything from 0 N to 42 N. V. None of the above can be concluded.

true I, II and III

Explanation:

The force is a vector quantity, by local it must be added as vectors, we can suppose several cases

.i) the vectors are colonial, so their sum is maximum

       F_max = 9 + 15 + 18

       F_max = 42 N

This is the maximum value

ii) the anti-parallel vectors giving a minimum value

     F_min = 15 + 9-18

     F_min = 6 N

iii) the vectors have angles between them, so we must use the Pythagorean theorem to find the resultant, which is an intermediate value between the two extreme values found.

Let's take a look at each statement

I) True This is the maximum value of the force if all the vectors are colonial

II) True The minimum value is 6 N, so zero can never be reached

III) True these bores are between the maximum values and the direction of the vectors, lower values occur when the forces have angular between them

IV) False. Force can never reach zero

V) False. Several of the above are conclusions of the exercise

the answer would be 32*f