For the following questions, if the answer requires a derivation, clearly show the equations, the calculation and units. Exact copying from the lecture notes is not encouraged - expand on definitions. Look at how many points are allotted before you embark on the answer. For example, 5 points means we are looking for a nicely fleshed out answer, with figures if that helps make the point.

1. In your own words, what is :

a) Greenhouse Effect
b) Global Warming
c) Climate Change
d) What is the scientific consensus on climate change?

a) Explain the details in your own words what you understand from it about energy balance.

b) Which arrows in Fig 12.5 is most directly related to the presence of greenhouse gases? 

3 a) What is positive feedback and negative feedback in the context of global warming?

b) Can you give 2 instances for each one, and explain why it is so? Use pictures if you need to.

4) a) What correlation has been observed between change in the earth's temperature and increasing carbon dioxide emission? is this positive or negative?

b) If the temperature of the earth rises enough so that the polar ice caops begin to melt, would this melting cause the global temperature to remain the same, drop or rise? Why?

5) a) What strategies are available to reduce global warming ?

b) Are there any consequences of such actions?

Assignment #4

For the following questions, if the answer requires a derivation, clearly show the equations, the calculation and units. Exact copying from the lecture notes is not encouraged - expand on definitions on your own.

1.) If 10 Kg of water per second undergoes a vertical drop of 50 metres, then what is the electrical power available assuming the efficiency of the turbine to be 80%?

2) What are the four components of a nuclear reactor we discussed in class, and what is their main purpose? What are the two purposes of water in a reactor core? Why does the uranium ore need to be enriched on the 235U content?

3. ) a) What is an isotope? Name an isotope involved in carbon dating? What is the basic principle behind carbon dating?

b) Suppose you have 10 grams of a radioactive isotope with a half-life of 5 days. How much this isotope would have decayed after 20 days? (5 points)

c) In the following fission reaction, what is the atomic number A and number of protons of nucleus Z of atom Y:

n + ²³⁵U _92→¹³⁵ I ₅₃+ ^A Y_z + 2n

4. The equation for the power from a wind turbine is : P= 2.83 x 10 ^-4 D² v³ kW

a) How big a blade would be needed on a wind turbine to produce 4000 kW in a 20m/s wind?

b) For the same blade size, what is the power if the wind increases to 40 m/s?