Which of the following statements is true? a)you are exposed to nuclear radiation every day. b)all natural radiation is at a level low enough to be safe. c)naturally occurring nuclear radiation is called background decay. d)most of the nuclear radiation you are exposed to in the environment is man-made.

B) All natural radiation is at a level low enough to be safe.

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.