Laura is a star runner of the school's track team. During a trial, her speed was measured to be 9.80 m/s. If Laura's mass is 45.2 kg, her kinetic energy during the trial was

KE = 2.17 E3 J

Explanation:

m = 45.2 kg

v = 9.8 m/s

KE = 1/2mv^2

KE = [(45.2 kg)(9.8m/s)^2]/2

KE = 2.17 E3 J

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.