Gravitation Class 9 in Tamil | One Shot Marathon | Vaathi Raid | Shimon Sir | Vedantu Master

Recent questions

• What is the law of gravitation?

  The law of gravitation, known as the universal law of gravitation, describes the gravitational force between two objects. It states that this force is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Mathematically, it is expressed as \( F = G \frac{m_1 m_2}{d^2} \), where \( G \) is the gravitational constant, approximately \( 6.67 \times 10^{-11} \, \text{N m}^2/\text{kg}^2 \). This means that as the distance between the objects increases, the gravitational force they exert on each other decreases significantly, illustrating how gravity weakens with distance.

• How is weight calculated?

  Weight is calculated using the formula \( \text{Weight} = \text{Mass} \times g \), where \( g \) represents the acceleration due to gravity. At the Earth's surface, \( g \) is approximately \( 9.81 \, \text{m/s}^2 \). This means that the weight of an object is directly proportional to its mass; as the mass increases, so does the weight. It's important to note that the value of \( g \) can vary slightly depending on geographical location, being lower at the equator and higher at the poles due to the Earth's shape and rotation.

• What are Kepler's laws?

  Kepler's laws of planetary motion describe how planets orbit the sun. The first law states that planets move in elliptical orbits with the sun at one focus. The second law indicates that a line segment joining a planet and the sun sweeps out equal areas during equal intervals of time, meaning that planets move faster when they are closer to the sun. The third law establishes a relationship between the orbital period of a planet and its distance from the sun, mathematically represented as \( T^2 \propto r^3 \), where \( T \) is the orbital period and \( r \) is the mean distance from the sun. Together, these laws provide a comprehensive understanding of planetary motion.

• What is acceleration due to gravity?

  Acceleration due to gravity, denoted as \( g \), is a constant that represents the rate at which objects accelerate towards the Earth due to gravitational force. It is approximately \( 9.81 \, \text{m/s}^2 \) at the Earth's surface. This value is independent of the mass of the object being measured, meaning that all objects, regardless of their mass, fall at the same rate in a vacuum. However, \( g \) can vary slightly based on location; it is generally less at the equator and more at the poles due to the Earth's rotation and shape. This consistency in \( g \) allows for accurate calculations of weight and gravitational effects.

• Why do planets move in elliptical orbits?

  Planets move in elliptical orbits due to the gravitational forces acting between them and the sun, as described by Kepler's First Law of planetary motion. This law states that the orbits of planets are not perfect circles but ellipses, with the sun located at one of the foci of the ellipse. The elliptical shape of the orbit results from the balance between the gravitational pull of the sun and the inertia of the planet moving through space. This dynamic interaction ensures that planets maintain their orbits while varying their distance from the sun, leading to the observed patterns of planetary motion.