Simple practice questions to get accustomed to significant numbers. This is important for all sciences. Attachments in PDF format.

Answer the following questions. The answer is to be given to the appropriate significant figures. a) 2.6 x 10 ^5 m + 2.1 x 10 ^ 3 km b) The volume of the moon is 2.21x10^19 m2. What is the radius? c) If there are 100 000 eletronic components on a semiconductor chip that measures 5.0 nm by 5.0 nm      i) How much area does each component occupy?      ii) If the individual components are square, how long is each on a side?

Simple practice questions to get accustomed to significant numbers. This is important for all sciences. Attachments in PDF format.

A 3.6 cm long radio antenna is added to the front of an aeroplane 41 m long. What is the overall length? Repeat this problem with an aeroplane length of 41.05 m. The answer must be to the correct significant figures. Full details are in the attachment below.

Simple practice questions to get accustomed to significant numbers and ensuring that numbers are not rounded too quickly. Attachments in PDF format.

a) "Machine epsilon" is a computer term describing the minimum quantity that can be added to 1 to give a different number. If machine epsilon for a certain computer is 0.000001, roughly how many significant figures does the computer carry in it's calculations? b) To see that it is important to carry more digits in intermediate calculations, determine the square root of 3 to the of power 3, to three significant figures in two ways. See attachment below for the full question

Practice question to get accustomed to significant numbers. Attachments in PDF format.

The answer should not contain more significant figure than the question. A carbon dioxide molecule contains a carbon atom and two oxygen atoms. Calculate its mass in: a) atomic mass units b)kilograms. (Amu of carbon = 14, Amu of oxygen = 16) See attachment below.

Steady-state temperature and relfectivity using thermal radiation. Solution in JPG format.

Consider venetian blinds that are painted black on one side and white on the other. Assume that the blinds are installed between two panes of glass, with a vacuum inbetween so that air and its convection have no effect on the problem. Assume that the reflectivity of the white side is 90% and that of the black side is 10%. How well does it work to turn the white side of the blinds outward when the room is already hot to reflect heat, while turning the black side outward to absorb heat when the room is too cold? Assume that the radiation from outside is 1 kW/m2. Find the steady-state temperatures due to just thermal radiation (Stefan-Boltzmann law).