How much power (energy per unit time) can be provided by a 75 m high waterfall with a flow rate of 10,000 l/s? give answer in kw rate given here is volume per unit time; 10,000 l/s mean that every second 10,000 l of water go through the water fall

Explanation:

It is given that flow rate is 10,000 L/s. As 1 L equals 0.001 .

Hence, flow rate will be 10 . Calculate mass of water flowing per second as follows.

        Mass flowing per second = density × flow rate

                                                   =

                                                   =

Also, energy provided per second will be as follows.

                      E = mgh

Putting the given values into the above formula as follows.

                   E = mgh

                      =  

                       =

or,                    = 7350 kW

Thus, we can conclude that energy per unit time provided will be 7350 kW.                

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.