Physics Online Course Essay
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1-How can you demonstrate that water is denser than ice without weighing them? What is the principle involved?
Release an ice cube in water; the ice cube will float. The ice cube will displace some water as it “pushes” the water away. The principle involved is displacement.
2-The density of water is a maximum at 4°C. Why is this property of water important for aquatic life?
The maximum density being attained at 4°C means that even if the water gets colder, the density will decrease.
Therefore, ice (when it forms) floats instead of sinks. This makes the continuity of aquatic life during winter possible.
3-When two different materials are given the same amount of heat will their temperatures increase by the same amount? Explain with reasons?
No. It depends on the ability of the materials to conduct heat.
4-It is generally observed that it is more difficult to cook food at high altitudes. Explain the possible reason for this?
In higher altitudes, there is lower pressure. This means that water will not boil at 100°C, but at a lower temperature, making your water not as hot as on sea-level, making cooking time longer.
5-What are the variable factors that affect the pitch (frequency) of a vibrating string? How are these factors controlled in a stringed musical instrument such as a violin?
The speed and wavelength of the waves formed by striking an object. A musician controls the frequency through the string’s tension and density, by pressing some of the strings.
6-If you want to see yourself fully in a plane mirror, the mirror needs to be only half your height. Draw a ray diagram showing how this is possible. Explain the diagram and principles you used.
The image in the mirror looks as if the figure is far away, when in fact, it is right in front of the mirror. This is because the light received by the eye traveled in a straight line as if it came from behind the mirror. The mirror is also laterally inverted, meaning the figure’s right will appear as the mirror image’s left.
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Dolan, G., Duffy, P. and Percival, A. (1996). Physics. United Kingdom: Heinemann.