Work, Energy & Heat
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Energy Stores & Systems
Type of Energy
Work is a process of energy conversion. In science, the word ‘work’ has a different
meaning from its everyday one. Work is done when energy is used or converted.
Work Done is a measure of how much energy (measured in joules, J) has been
converted or transferred. Energy is used when we move an object. For work to be
done, a constant force must act on an object and the object must move a distance
in the direction of the force.
Work Done is a scalar quantity although force is a vector quantity.
PRINCIPLE OF CONSERVATION OF ENERGY
PRINCIPLE OF CONSERVATION OF ENERGY
Energy cannot be created nor destroyed in any process. It can only be converted from one form to another or transferred from one body to another, but the total amount of energy of a system is constant.
At the top of the hill, the roller coaster car is stationary, so where has all its kinetic energy gone?
It has been converted to potential energy. As the roller coaster car begins its descent on the other side of the hill, the potential energy begins to be converted back to kinetic energy, and the car gathers speed until it reaches the bottom of the hill. Back at the bottom, all the potential energy the roller coaster car had at the top of the hill has been converted back into kinetic energy.
The roller coaster has potential energy because of the gravitational forces acting on it, so this is often called gravitational potential energy.
The roller coaster car’s total mechanical energy, which is the sum of its kinetic and potential energies, remains constant at all points of the track (ignoring frictional forces). The combination of the kinetic and potential energies does vary, however. When the only work done on an object is performed by conservative forces, its mechanical energy remains constant, whatever motions it may undergo.
Heat is a form of energy whereas Temperature is a measurement of the degree of hotness of a
body.
Heat flows from a region of higher temperature to a region of lower temperature. Regions of equal temperature are in thermal equilibrium.
Heat Transfer - Conduction, Convection & Radiation
Heat Transfer - Conduction, Convection & Radiation
Good extra notes on Convection
https://www.tskvgss.edu.hk/elearning%20material1920/s3/w2/PHY/S3_PHY_NOTE_4.2_ENG.pdf
Air trapped between blankets
Vacuum Flask
The Green House Effect
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