An object undergoes simple harmonic motion along the x-axis shown above, where x = 0 is the object's equilibrium position. Which of the following graphs best shows the relationship between the object's acceleration a and its displacement x from equilibrium? (Assume positive acceleration to be directed to the right.)

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Explanation:

Simple harmonic motion is described by a differential equation in which acceleration is proportional to the opposite of displacement. The displacement-acceleration graph looks like a line with negative slope.

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.