How much heat flows per second through a well lagged bar of alummium of thermal cond7ctivity 230W ,the bar has length of 300mm and a cross sectional area of 100 mm² with a temorature difference of 40°c between the ends of the bar

The amount of heat flows per second in given aluminium bar is 3.066 .

Explanation:

We know that , amount of heat flowing per second is given by

 Where A = area =  

             K = Thermal conductivity =

             L = Length =

  Upon substituting these values in above equation we get ,

         Heat flowing per second =

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.

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this