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5. Answer any eight of the following parts (a), (b), (c), etc - Leaving Cert Physics - Question 5 - 2020
Question 5
5. Answer any eight of the following parts (a), (b), (c), etc. a) Explain Archimedes’ principle. The diagram may help you answer. b) What is meant by latent heat?
Worked Solution & Example Answer:5. Answer any eight of the following parts (a), (b), (c), etc - Leaving Cert Physics - Question 5 - 2020
Step 1
Explain Archimedes’ principle.
Answer
Archimedes' principle states that when an object is immersed in a fluid, it experiences an upward force, known as buoyancy, which is equal to the weight of the fluid that is displaced by the object.
In the provided diagram, we can see a setup with a 5 N weight on one side and a 3 N weight on the other side, both connected to spring scales. The apparent loss in weight (2 N) when the objects are submerged corresponds to the weight of the fluid displaced. This means that the upward force acting on the object in the water, termed upthrust, is equal to the weight of the 2 N of water displaced.
Thus, we can summarize:
- Upthrust (buoyant force) = Weight of the fluid displaced.
- Apparent loss in weight = Weight in air - Weight in fluid.
Step 2
What is meant by latent heat?
Answer
Latent heat refers to the amount of heat energy required to change the state of a substance without changing its temperature. This energy is absorbed or released during phase transitions, such as melting, boiling, or evaporating.
For example:
- To convert ice at 0°C to water at 0°C, latent heat is absorbed.
- When water at 100°C turns to steam, it also absorbs latent heat.
The term 'latent' implies that this heat is hidden or not evident in temperature increase, but it plays a crucial role in phase changes.