Chapter 22, Problem 45A

At a certain location, the solar power per unit area reaching Earth’s surface is $200W/m^2$, averaged over a 24-hour day. Consider a house with an average power requirement of 3 kW with solar panels on the roof that convert solar power to electric power with 25 percent efficiency. Show that a solar collector area of 60 square meters will meet the 3 kW requirement.

To determine

Energy conversion in car’s engine, described by the sequence A. (Chemical-Thermal-Mechanical)

Explanation of Solution

Introduction:

The energy conversion or the energy transformation is that the process of adjusting one sort of energy to a different. The energy produces certain changes within a system. Changes within the total energy of systems can only be accomplished by adding or removing the energy from them because the energy may be a quantity which is conserved.

The energy in many of its forms could also be utilized in the natural processes, it provides some services to the society like heating, the refrigeration & the sunshine, and it performs the mechanical work to work the machines.

The internal combustion in car’s engine converts the potential energy into gasoline and oxygen, then into thermal energy which is transformed into the energy (Mechanical energy). this mechanical energy accelerates the vehicle by increasing its K.E. and it causes the pressure due to which the pistons work.

In this picture we see how energy is being transferred within the car engine. We will see that the car’s engine transfers the energy (chemical energy) which is stored within the fuel into the K.E. of expanding gas via combustion within the engine and the wheels.

Conclusion:

The heat energy changes into the mechanical energy which moves the car and therefore the chemical energy that stored within the fuel changes by burning into the thermal (the heat) energy within the car engine.