Understanding the Apparent Weight of an Object in Water
When an object is submerged in a fluid, such as water, its apparent weight changes. This phenomenon is known as buoyancy and has significant implications in various fields, including engineering, physics, and scientific research. In this article, we will explore the concept of apparent weight in water and demonstrate how it can be calculated for a given object. We'll apply this understanding to a specific scenario involving a house brick.
What is Apparent Weight?
Apparent weight refers to the weight of an object as perceived or measured when it is immersed in a fluid, such as water. It takes into account the buoyant force exerted by the fluid, which causes the object's apparent weight to differ from its actual weight in air.
Calculation of Apparent Weight in Water
The formula to calculate the apparent weight of an object in a fluid is as follows:
Apparent weight in water Weight in air - Weight of water displaced
Step-by-Step Calculation
Given that a house brick has a volume of 1900 cm3 and a weight in air of 80 N, we can calculate its apparent weight in water using the following steps:
Calculate the weight of the water displaced by the brick: Volume of water displaced Volume of brick 1900 cm3 Density of water 1.00 g/cm3 1000 kg/m3 Weight of water displaced Volume × Density × Acceleration due to gravity Weight of water displaced 1900 cm3 × 1000 kg/m3 × 9.81 m/s2 Weight of water displaced 1900 × 10-6 m3 × 1000 kg/m3 × 9.81 m/s2 Weight of water displaced 1.8639 NNow, let's calculate the apparent weight in water:
Apparent weight in water Weight in air - Weight of water displaced
Apparent weight in water 80 N - 1.8639 N Apparent weight in water 78.1361 N
Explanation of Buoyancy Force
Buoyancy force is the upward force exerted by a fluid on an object fully or partially submerged in it. According to Archimedes' principle, the buoyant force is equal to the weight of the fluid displaced by the volume of the object. This principle can be stretched to explain why the apparent weight changes when an object is submerged.
In the case of the house brick:
If the weight of the water displaced (1.8639 N) is less than the brick's weight in air (80 N), the apparent weight in water will be less than the brick's weight in air. If the weight of the water displaced is greater than the brick's weight in air, the brick would float, and the apparent weight would be negative. If the weight of the water displaced is equal to the brick's weight in air, the brick would be neutrally buoyant and float at the surface.Conclusion
Calculating the apparent weight of an object in water is a fundamental concept in fluid mechanics. It is crucial for various applications, from designing ships and submarines to assessing the stability of structures in aquatic environments. Understanding this principle helps us appreciate the forces at play in everyday situations and contributes to the broader field of physics.