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Mass and Weight
This section delves into the concepts of mass and weight, illustrating the distinction between the two through practical examples and fundamental physics principles. It begins with a multi-flash photograph of a falling ball, showcasing the acceleration caused by gravity. The gravitational force, or weight, acting on an object with mass is introduced and defined in Newtons (N).
Every object near the Earth’s surface is influenced by the Earth’s gravitational pull, approximately 9.8 N per kilogram of matter. This means a 1 kg object has a weight of 9.8 N. The concept of free fall and acceleration due to gravity (symbolized as g) is explored, with g being roughly 9.8 m/s².
Calculating Weight and Gravitational Field Strength
The calculation of an object’s weight from its mass involves multiplying the mass (m) by the acceleration due to gravity (g). This relationship is expressed as W = mg. The gravitational field strength is defined as the force exerted per unit mass, with the Earth’s surface value being 9.8 N/kg, often rounded to 10 N/kg.
Distinguishing Mass and Weight
A crucial part of the section is understanding the difference between mass and weight. Mass measures the amount of matter in an object (in kilograms), while weight is the gravitational force on the object (in Newtons). An object’s mass remains constant regardless of location, but its weight varies with the gravitational strength of the location. This distinction is exemplified by comparing the weight of an object on Earth, the Moon, and Jupiter.
Figures and Quick Questions
Figure 1: Demonstrates the increasing speed of a falling ball.
Figure 2: Shows a weighing balance used to compare weights and determine mass.
Quick questions are provided to reinforce understanding, prompting readers to list differences between mass and weight and consider how the mass and weight of a bag of sugar would change on the Moon and Jupiter.
This comprehensive explanation of mass and weight, supported by visual aids and practical examples, aims to solidify foundational physics concepts for IGCSE students.
17 окт 2024
