Questions

Life Cycle costing includes the costs from each phase of the project life cycle when the total investment costs are calculated. Answer A is incorrect because an opportunity cost is the difference between a chosen investment and the one that is passed up. Answer B is incorrect because sunk costs are costs that have been incurred and cannot be reversed. Answer C is incorrect because net present value (NPV) is the present value of cash inflows(benifits) minus the present value of cash outflows (costs).

A number of possible explanations for why manhole covers are round include :

1. A round manhole cover cannot fall through its circular opening, whereas a square, rectangular, or oval manhole cover could fall in if it were inserted diagonally in the hole.

2. Circular covers don’t need to be rotated or precisely aligned when placing them on the opening.

3. A round manhole cover is easily moved and rolled.

4. Human beings have a roughly circular cross-section.

5. Round tubes are the strongest shape against the compression of the earth around them, so the cover of the tube would naturally be round as well.

6. It’s easier to dig a circular hole.

Pericles

The major greenhouse gases (GHG’s) solely responsible for greenhouse effect are Carbon dioxide, Ozone, Methane and Water vapor. Although these gases comprise 1% of our atmosphere, they act like a thick warm blanket outside that surrounds this planet and regulate climate control. Greenhouse effect is not bad. In fact, it is needed for all of us to survive on planet Earth. In short, the greenhouse effect is nothing but a naturally occurring process designed by nature that aids in heating earth’s surface and helps to maintain ecological balance.

Now, while some of that heat dissipates into space, some of it burns along the atmosphere, and some of it penetrates the atmosphere and finds its way into the lower atmosphere and the planet’s surface. This in turn raises the average temperature of the Earth. Therefore, the increase in the Earth’s surface temperature due to increase in the number of greenhouse gases leads to global warming.

Causes of Green House Effects ::

* Burning of Fossil Fuels

* Deforestation 

* Increase in Population

* Farming

* Industrial Waste and Landfills.

A mixture is made from different substances that are not chemically joined.Compound:

•Two or more elements combine together chemically to form a new substance called compound.

•The different elements are chemically joined together.•Compounds are homogeneous, i.e. their properties are the same throughout

•The compound has properties different from the elements it contains.

•It can only be separated into its elements using chemical reactions. (not using physical methods)

•During the formation of a compound from its elements, a certain amount of energy in the form of heat, light, electricity is either absorbed or evolved