# CHAPTERS BY WACEK KIJEWSKI

# # Chapter 13 Problems

Below are examples of some problems involving basic measurements. Remember, it is your task to design and plan the experiments.

#### **Problem 1: Relative density**

You are given three objects. Which one has the highest density?

#### **Problem 2: Pressure exerted by stool legs**

The tiles of the laboratory are of a good quality. The legs of the stools, on which you are sitting right now, exert a great pressure on the tiles. Determine, by taking the relevant measurements, the pressure of the stool on the floor when you sit on it.

#### **Problem 3: Measuring the length of a filament of a bulb**

You are asked to determine the length of the filament of the bulb as accurately as possible using a power supply, a lens, a screen and a ruler.

After you have determined the length you should check the value found by measuring the length directly as well. Try to avoid parallax error.

#### **Problem 4: Measuring the diameter of the Sun**

You are asked to design and perform an experiment in which the diameter of the Sun is determined. Use a lens, a screen, the Sun and a ruler. In the calculations you need to include the distance between the Sun and the Earth. After you have found a value for the diameter of the Sun, use a book of constants or Chapter IX to see whether the value found by you is accurate enough.

Do you like anecdotes, interesting and challenging problems, fun facts, puzzles, jokes related to metric system and measurement? Read them in the 2006 on-line edition of "SI Units, Conversion and Measurement Skills",186 pp.