Why is force a vector?

Question

"We have focused our discussion on one-dimensional motion. **It is natural to assume that for three-dimensional motion, force, like acceleration, behaves like a vector.**"- (Introduction to Mechanics) Kleppner and Kolenkow We learn it very early in the course of our study that Force is vector; But, if I were the physicist defining the the Newton's second law (experimentally) and analysing the result F=ma, how would I determine whether Force is vector or scalar(especially in 3-D). Actually, when I read the aforementioned sentences from the book, I wanted to know why do the authors expect it to be **natural** for us to think that in 3-D "Force" behaves like a vector. I know **a**(acceleration ) is vector and mass a scalar and scalar times vector gives a new vector but is there another explanation for this?

Answer 1

Because forces require a magnitude and a direction for their description.

Jim