Фізика 7 НУШ. Лабораторна робота №10. Перевірка умов плавання тіла. Урок №65

Summary

In this final laboratory session of the academic year, students explore the conditions under which objects float, sink, or float within a liquid. The experiment involves measuring the volume and mass of a test tube filled with sand, determining its density, and observing how it interacts with water. The session consists of three key experiments: identifying when an object sinks, floats in the liquid, and floats on the surface. Students analyze the forces acting on the object, including gravity and buoyant force, and compare the density of the object to the density of water to determine its behavior. The session concludes with a review of the findings and a homework assignment.

Takeaways

• 😀 The objective of the experiment is to determine the conditions under which an object floats on the surface, floats within the liquid, or sinks.
• 😀 The experiment is conducted remotely, with the teacher performing the measurements via video and students processing the results.
• 😀 The first experiment involves determining the condition under which an object sinks in the liquid by measuring the volume of displaced water and calculating the object's density.
• 😀 For the first experiment, the test tube with sand sinks because its density is greater than the density of water (1.2 g/cm³ vs. 1 g/cm³).
• 😀 In the second experiment, the test tube is adjusted to float inside the liquid by removing some of the sand, and the density of the object is calculated to be close to the density of the liquid.
• 😀 The third experiment involves making the test tube float on the surface of the liquid by removing more sand, resulting in a density less than the liquid's density.
• 😀 In each experiment, students are required to fill out a table with measurements such as the volume of water, the volume displaced by the object, and the object's density.
• 😀 Students must perform calculations such as the difference between initial and final water levels to determine the volume of the test tube and use mass/volume to calculate the density.
• 😀 Force diagrams are drawn in each experiment to illustrate the forces acting on the test tube, including gravity and buoyancy (Archimedes' force).
• 😀 The final analysis involves comparing the densities of the objects with the density of water and determining if the object sinks, floats within the liquid, or floats on the surface based on these comparisons.

Q & A

What is the main purpose of the laboratory experiment described in the transcript?

The main purpose of the laboratory experiment is to experimentally determine the conditions under which a body floats on the surface of a liquid, floats inside a liquid, or sinks in the liquid.

What are the pieces of equipment used in the experiment?

The equipment includes a test tube with a stopper, string, dry sand, a measuring cylinder with water, and a set of scales.

How is the first experiment set up to determine under what conditions a body sinks in liquid?

The first experiment involves measuring the volume of water in the cylinder, filling the test tube with sand, and then submerging the test tube to observe its behavior. The volume of water displaced by the test tube is then measured, followed by calculating the mass and density of the test tube with sand.

What is the significance of calculating the density of the test tube with sand?

Calculating the density helps determine whether the test tube will float or sink in the liquid. If the density of the test tube with sand is greater than that of water, the test tube will sink.

What role does Archimedes' principle play in this experiment?

Archimedes' principle is used to explain how the liquid exerts an upward buoyant force on the test tube, which is equal to the weight of the liquid displaced. The experiment investigates whether this buoyant force is enough to counteract the weight of the test tube, leading it to float, sink, or stay submerged.

In the second experiment, what condition is tested to determine when a body floats inside a liquid?

In the second experiment, the test tube is adjusted by removing sand to ensure it floats inside the liquid. The mass and volume are then measured again, and the density is calculated to observe its behavior in the liquid.

What is the procedure for the third experiment, and what does it demonstrate?

The third experiment involves further removing sand from the test tube so that it floats on the surface of the liquid. This demonstrates the condition under which an object floats on the surface of the liquid rather than sinking or floating within it.

How does the density of water compare to the density of the test tube in the first experiment?

In the first experiment, the density of the test tube with sand is greater than the density of water, which causes the test tube to sink.

What are the key factors that influence the accuracy of the experiment?

Factors that influence the accuracy include the precision of measurements, the consistency in the volume of water, the accuracy of weighing the test tube and sand, and ensuring that the experiment is conducted according to the safety rules and instructions.

What kind of analysis is required in the conclusion of the experiment?

In the conclusion, students are expected to analyze the results of the three experiments, comparing the conditions under which a body floats on the surface, floats inside, or sinks. They should also reflect on the factors affecting the accuracy of the experiment and explain the observed behaviors based on the principles of density and buoyancy.