Professional Courses
Industry-relevant training in Business, Technology, and Design to help professionals and graduates upskill for real-world careers.
Categories
Interactive Games
Fun, engaging games to boost memory, math fluency, typing speed, and English skillsβperfect for learners of all ages.
Typing
Memory
Math
English Adventures
Knowledge
Enroll to start learning
Youβve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Introduction to the Gravitational Constant
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Today, we're discussing the gravitational constant, symbolized as G. Can anyone tell me how gravitational attraction is calculated?
Is it related to the mass of the two objects and the distance between them?
Exactly! The gravitational force between two objects depends on their masses and the distance that separates them, according to Newton's law of universal gravitation. G is the factor that applies to this relationship.
Why is G considered a constant?
G is termed a constant because it does not change regardless of the mass or distance involved in the interaction. Its value remains consistent at approximately 6.67 Γ 10^(-11) N mΒ²/kgΒ².
Who first measured this value?
Good question! The gravitational constant was first experimentally determined by Henry Cavendish in 1798 using a special apparatus. Let's explore how he did that.
Henry Cavendish's Experiment
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Cavendish used a torsion balance. Can anyone visualize how that apparatus worked?
Was it a pendulum or something similar?
Yes! It was a horizontal bar suspended from a wire with lead spheres attached at each end. When larger spheres were placed next to them, they exerted a gravitational force which made the bar twist.
How did he measure the angle of rotation?
Cavendish observed the angle at which the bar rotated, and this allowed him to calculate the gravitational force between the spheres, leading him to determine G.
And from that, he calculated the mass of the Earth too?
Absolutely! This was a monumental experiment that provided key insights into gravity and mass.
The Value and Importance of G
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
So, to summarize, the gravitational constant is crucial for defining the strength of gravity. How does this affect our calculations in physics?
It helps us determine the force between any two masses.
And itβs essential for understanding celestial mechanics too!
Correct! Applications of G range from calculating orbits of planets to predicting movements of galaxies. It's the cornerstone of gravitational physics.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
The gravitational constant, denoted as G, is a fundamental constant in physics that describes the strength of gravitational attraction between two masses. It was determined experimentally by Henry Cavendish in the late 18th century using a balance technique and remains a critical value in the field of gravitational physics, helping to form the basis of Newton's law of gravitation.
Detailed
The Gravitational Constant
The gravitational constant (G) is a key figure in the universal law of gravitation, signifying the proportionality factor that relates the gravitational force between two masses to the product of their masses and the inverse of the square of the distance between them. The value of G was first determined through experiments conducted by Henry Cavendish in 1798, making use of a torsion balance to measure the tiny gravitational forces between lead spheres.
Cavendishβs Experiment
Cavendish's apparatus involved a horizontal bar suspended from a wire, with small lead spheres attached at each end. Large lead spheres were then placed near the smaller ones. Due to gravitational attraction, the bar rotated slightly, and the angle of rotation could be measured. This experiment allowed Cavendish to not only measure G accurately but also estimate the mass of the Earth, confirming the efficacy of the gravitational theory.
Current Value
The currently accepted value of the gravitational constant is:
G = 6.67 Γ 10^(-11) N mΒ²/kgΒ²
This value is fundamental for calculations involving gravitational forces in astrophysics and cosmology.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Cavendish's Experiment
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
The value of the gravitational constant G entering the Universal law of gravitation can be determined experimentally and this was first done by English scientist Henry Cavendish in 1798. The apparatus used by him is schematically shown in Fig.7.6...
Detailed Explanation
Henry Cavendish conducted a groundbreaking experiment to measure the gravitational constant G in 1798. He designed a device that consisted of a horizontal bar suspended from a wire, with small lead spheres attached to each end of the bar. When larger lead spheres were brought near the smaller spheres, the gravitational attraction caused the bar to rotate, due to the torque generated on it. By measuring the angle of rotation, Cavendish could quantify the gravitational force between the masses, which allowed him to calculate G.
Examples & Analogies
Imagine you have two magnets and you want to measure their pulling force. Instead of just using scales to weigh them, you use a string and a piece of paper to see how much the paper bends when you bring the magnets close. This bending indicates how strong the magnets pull on each other, just like Cavendish observed how the bar rotated to indicate the gravitational force.
Understanding G and its Measurement
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
The bar AB has two small lead spheres attached at its ends. The bar is suspended from a rigid support by a fine wire. Two large lead spheres are brought close to the small ones but on opposite sides as shown...
Detailed Explanation
In Cavendish's setup, the gravitational force between the large and small spheres created a torque on the suspended bar. The experiment measured the angle through which the bar twisted, a direct indication of the gravitational force at play. With the known distance between the masses and the measured angle of twist, Cavendish could derive a value for G, leading to a better understanding of gravitational interactions.
Examples & Analogies
Think of spinning a playground swing. If you sit on one side and someone on the other swings their legs to push you, you'd feel the twist. Similar to how Cavendish felt the twist of the bar, he could relate that twist to how strongly the masses attracted each other, telling us how strongly gravity works between those masses.
Value of the Gravitational Constant
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Since Cavendishβs experiment, the measurement of G has been refined and the currently accepted value is G = 6.67Γ10^-11 N m2/kg2.
Detailed Explanation
The gravitational constant, G, is a crucial parameter in Newton's law of gravitation. The value of G indicates how strong the gravitational force is between two masses. Currently, it stands at 6.67Γ10^-11 N mΒ²/kgΒ². This low value means that gravity is a relatively weak force compared to other fundamental forces like electromagnetism. Understanding G is vital for calculating the gravitational pull between objects of significant mass, like planets and stars.
Examples & Analogies
If you think about gravity, it's like a soft glue holding things together. Just as you need a lot of glue to hold heavy things, you need masses that are large (like planets) for gravity to be strong enough to feel significant. The small value of G assures us that even a tiny fraction of mass can result in a weak force, which is why we donβt notice gravity from small objects like books or chairs.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Gravitational Constant (G): Measures the strength of gravitational attraction between two masses.
-
Cavendish Experiment: The first experiment that accurately determined the value of G.
-
Newton's Law of Universal Gravitation: Describes how masses interact via gravity.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
Cavendish's experiment utilized a torsion balance to measure gravitational forces, allowing for the calculation of G.
-
The gravitational force between two objects can be calculated using the formula F = G * (m1 * m2) / rΒ².
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
π΅ Rhymes Time
-
G keeps it grand in the gravity land, 6.67, it holds tight, for masses in orbit and in flight.
π Fascinating Stories
-
Imagine Cavendish in a dark lab with heavy lead balls, twisting wires, capturing gravityβs calls, he found G, a key to gravity's thrall.
π§ Other Memory Gems
-
Remember G as 'Great Gravitational Force' β with a value that stays consistent, never off course.
π― Super Acronyms
G
- Gravitational constant; M
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Gravitational Constant (G)
Definition:
A constant that measures the strength of gravitational attraction between two masses, approximately equal to 6.67 Γ 10^(-11) N mΒ²/kgΒ².
-
Term: Cavendish Experiment
Definition:
An experiment conducted by Henry Cavendish to measure the gravitational constant using a torsion balance.
-
Term: Universal Law of Gravitation
Definition:
A law stating that every mass attracts every other mass with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.