NCERT CLASS 11 PHYSICS CHAPTER 7 – GRAVITATION IN-TEXT QUESTIONS AND ANSWERS 1. What is gravitation? Gravitation is the universal force of attraction that exists between any two objects having mass. It is responsible for the motion of planets around the Sun, the Moon around the Earth and objects falling towards the Earth. 2. State Newton’s universal law of gravitation. Newton’s universal law of gravitation states that every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. Mathematically, F = Gm₁m₂/r² Where: F = Gravitational force m₁ and m₂ = Masses of the two bodies r = Distance between their centres G = Universal gravitational constant 3. What is the value and SI unit of the universal gravitational constant? The value of the universal gravitational constant is: G = 6.67 × 10⁻¹¹ N m² kg⁻² Its SI unit is newton metre squared per ki...

  NCERT CLASS 11 PHYSICS CHAPTER 8 – MECHANICAL PROPERTIES OF SOLIDS IN-TEXT QUESTIONS AND ANSWERS 1. What are mechanical properties of solids? Mechanical properties of solids describe how solid materials behave when external forces are applied to them. These properties include elasticity, plasticity, strength, stiffness and the ability to resist deformation. 2. What is elasticity? Elasticity is the property of a material by which it regains its original shape and size after the deforming force is removed, provided the deformation is within its elastic limit. Example: A steel spring returns to its original shape when the stretching force is removed. 3. What is plasticity? Plasticity is the property of a material by which it does not regain its original shape and size completely after the deforming force is removed. Example: Clay can be moulded into different shapes and retains the new shape. 4. Define stress. Stress is the restoring force developed per unit area inside a body when ...