Chapter 1: Problem 35
The dimensions of universal gravitational constant are (a) \(\left[\mathrm{ML}^{-3} \mathrm{~T}^{2}\right]\) (b) \(\left[\mathrm{ML}^{2} \mathrm{~T}^{-3}\right]\) (c) \(\left[\mathrm{M}^{-1} \mathrm{~L}^{3} \mathrm{~T}^{-2}\right]\) (d) \(\left[\mathrm{M}^{2} \mathrm{~L}^{2} \mathrm{~T}^{-2}\right]\)
Short Answer
Step by step solution
Understand the formula for gravitational force
Determine the dimensions of known quantities
Write the dimensions into the gravitational formula
Solve for the dimensions of G
Choose the correct option
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Universal Gravitational Constant
It was first introduced by Sir Isaac Newton in his law of universal gravitation.
This constant helps quantify the strength of gravity between two masses.
The value of \( G \) is approximately \( 6.674 \times 10^{-11} \, \text{Nm}^2/\text{kg}^2 \).
Using dimensional analysis, the dimensions of \( G \) can be derived to be \([M^{-1} L^3 T^{-2}]\). To understand this, recall that in the formula \( F = G \frac{m_1 m_2}{r^2} \), force \( F \) is dimensionally \([MLT^{-2}]\), mass \( m \) is \([M]\), and distance \( r \) is \([L]\). By rearranging to solve for \( G \), you find \( G \) to have its unique dimensional expression, indicative of how it balances mass, distance, and force in gravitational interaction equations.This measurement of \( G \) is critical in astrophysics and cosmology, underpinning calculations of satellites, planetary movements, and even the behavior of galaxies. Understanding \( G \) is pivotal for students preparing for exams in physics, particularly when delving into gravitational forces in competitive settings.
Newton's Law of Gravitation
This is formally expressed as \( F = G \frac{m_1 m_2}{r^2} \), where \( F \) is the gravitational force between two bodies, \( m_1 \) and \( m_2 \) are the masses, \( r \) is the distance between the masses, and \( G \) is the gravitational constant.
The inverse-square law component of Newton's formula is particularly significant as it implies that the gravitational force diminishes with the square of the distance from the object. This principle explains why planets continue to maintain their orbits and why we stay rooted to the Earth's surface.
Newton's Law of Gravitation elegantly demonstrated how forces work both on small scales, like objects on Earth, and on massive scales, like planetary bodies in space. As such, it is a fundamental concept for physics competitive exams; students must understand both how to apply the formula to problems and the theory behind the force of gravity itself for a comprehensive grasp.
Physics Competitive Exams
Here are some tips:
- Master dimensional analysis: Being able to break down and understand dimensions will aid in solving complex physics problems efficiently.
- Practice problem-solving: Engage with a variety of problems involving gravitational forces to develop both proficiency and speed.
- Conceptual clarity: Ensure a strong grasp of fundamental concepts like gravitational potential energy and how it is influenced by mass and distance.
- Time management: Learn to balance detailed calculations with the necessity for quick, accurate problem-solving.
As you prepare, focus on building a strong foundation in both theoretical concepts and practical applications, as both are pivotal in achieving success in physics competitions.