At a resting pulse rate of 79 beats per minute, the human heart typically pumps about 67 ml of blood per beat. blood has a denstity of 1060 kg / m3. circulating all of the blood in the body through the heart takes about 1 min for a person at rest. (a) how much blood is in the body? give answer in cubic meter(m3) (b) on average, what mass of blood does the heart pump with each heart beat? give answer in kilograms (kg).
hint:
1000ml=1l
1000l=1m^3(cubic meter)

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.