Please help me with 10,11,12

Explanation:

10) II

Vectors are added by putting the tail of the second at the head of the first. The result is the vector from the tail of the first to the head of the second

11) IV

Negating a vector will give it the same magnitude but opposite direction. Then treat as addition as in Q 10

12) B  any value between 3 N and 17 N

Magnitude will be 3 when the vectors are co-linear but opposite in direction.

Magnitude will be 17 when the vectors are co-linear and in the same direction.

Magnitudes between 3 and 17 will occur when the vectors are not co-linear

yup its correct its: c) b b

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.