The Intensity of solar radiation at the Earth's orbit is 1370 W/m^2. However, because of the atmosphere, the curvature of the Earth, and rotation (night and day), the actual intensity at the Earth's surface is much lower. At this moment, let us assume the intensity of solar radiation is 800 W/m^2. You have installed solar panels on your roof to convert the sunlight to electricity.
(a) If the area of your solar panels is 4 m^2, how much power is incident on your array?
(b) Unfortunately, solar panels are only about 20% efficient i. e only 1/5 of the light is converted to electricity. This being the case, how much electrical power are you actually producing for your home at this moment?

a) Pi = 3200 w    

b) Pe = 640 w

Explanation:

Solar radiation is      800 w/m²

a) Area of solar panel is  4 m²

Then Power Incident is:

Pi = Solar radiation  x   Area of solar panel array ,  then

Pi  = 800 w/m²  *  4  m²

Pi = 3200 w    or    Pi  = 3.2 Kw

b) Solar panels efficiency is  20%

Electricity production: Pe

Pe = Pi * η         where  η is efficiency    η = 20 %    η = 0,2

Pe = 3200 w * 0,2

Pe = 640 w        or        Pe  = 0,640 Kw

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.