At a steam power plant, steam engines work in pairs, the heat output of the first one being the approximate heat input of the second. the operating temperatures of the first are 750◦c and 440◦c respectively, and of the second 415◦c and 270◦c.

The rate at which coal burned is 111.12 kg/s.

Explanation:

Given that,

First initial temperature  =750°C

First final temperature =440°C

Second initial temperature  =415°C

Second final temperature =270°C

Suppose If the heat of combustion of coal is , at what rate must coal be burned if the plant is to put out 950 MW of power? Assume the efficiency of the engines is 65% of the Carnot efficiency.

The work done by first engine is

The work done by second engine is

Total out put of the plant is given by

Put the value into the formula

....(I)

We need to calculate the efficiency of first engine

Using formula of efficiency

We need to calculate the efficiency of second engine

Using formula of efficiency

Put the value of efficiency for first and second engine in the equation (I)

We need to calculate the rate at which coal burned

Using formula of rate

Hence, The rate at which coal burned is 111.12 kg/s.

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees. 

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.