State the Universal Law of Gravitation – Class 11 Physics

Yashwant Parihar,

Gravitation is an important topic in Class 11 Physics that helps us understand why objects fall on Earth and how planets move around the Sun. In this chapter, students learn to state the universal law of gravitation, explain Newton’s universal law of gravitation, and understand its real-life applications.

In this article, we will state and explain the universal law of gravitation in simple words, derive the universal law of gravitation step by step, and also discuss the importance of the universal law of gravitation for exams and practical understanding.

State Universal Law of Gravitation

The Universal law of gravitation was given by Sir Isaac Newton.

Statement: Every particle attracts another particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.

Explain Newton’s Universal Law of Gravitation

Let two bodies of masses m₁ and m₂ be separated by a distance r.

The gravitational force is directly proportional to the product of masses m1 and m2.

F∝m1m2F ∝ m_1 m_2

The gravitational force is inversely proportional to the square if ther distance to the centre.

F∝1r2F ∝ \frac {1}{r^2}

By combining both equations-

F∝m1m2r2F ∝ \frac {m_1m_2}{r^2}

Removing proportionality by introducing a constant G:

F∝Gm1m2r2F ∝ G \frac {m_1m_2}{r^2}

Where:

  • F = Gravitational force
  • G = Universal gravitational constant
  • m₁, m₂ = Masses of two bodies
  • r = Distance between their centres

Value of G:

G=6.67×10−11 Nm2kg−2G = 6.67 \times 10^{-11} \, Nm^2kg^{-2}

Importance of the Universal Law of Gravitation

The importance of the universal law of gravitation is very high in physics because it helps us to:

  • Explain why objects fall toward the Earth
  • Understand the motion of planets around the Sun
  • Calculate escape velocity
  • Study satellite motion
  • Explain ocean tides
  • Understand orbital velocity
Physics Class 11