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Chapter Analysis
Intermediate15 pages • EnglishQuick Summary
The chapter on Gravitation in Class 11 Physics explores the universal law of gravitation, which describes the force of attraction between any two masses. It discusses concepts like gravitational potential energy, escape speed, and satellite motion. The chapter also covers Kepler's laws of planetary motion and how they relate to gravitational forces. Practical examples and problems are provided to help students understand the application of these gravitational principles.
Key Topics
- •Universal Law of Gravitation
- •Gravitational Potential Energy
- •Kepler's Laws of Planetary Motion
- •Escape Speed
- •Satellite Motion
- •Acceleration due to Gravity
- •Gravitational Field and Potential
- •Weightlessness
Learning Objectives
- ✓Understand the universal law of gravitation and its applications.
- ✓Explain the concept of gravitational potential energy and its calculation.
- ✓Apply Kepler's laws to explain planetary motion.
- ✓Calculate escape speed and understand its implications.
- ✓Comprehend satellite dynamics and their relation to gravity.
- ✓Discuss the effects of gravity beneath and above Earth's surface.
Questions in Chapter
Suppose there existed a planet that went around the Sun twice as fast as the earth. What would be its orbital size as compared to that of the earth?
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Io, one of the satellites of Jupiter, has an orbital period of 1.769 days and the radius of the orbit is 4.22 × 10^8 m. Show that the mass of Jupiter is about one-thousandth that of the sun.
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Does the escape speed of a body from the earth depend on (a) the mass of the body, (b) the location from where it is projected, (c) the direction of projection, (d) the height of the location from where the body is launched?
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Additional Practice Questions
Explain why Newton's law of gravitation can be considered a universal law.
mediumAnswer: Newton's law of gravitation is considered universal because it applies to all masses, regardless of their nature or location in the universe. It describes how any two masses attract each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.
Describe how gravitational force varies inside the earth.
hardAnswer: Inside the earth, the gravitational force decreases as one moves towards the center. This is because the effective mass attracting the object decreases as the layers are passed. At the center of the earth, the gravitational force is zero because there is mass all around the object pulling it equally in all directions.
What is the significance of Kepler's laws in understanding planetary motion?
mediumAnswer: Kepler's laws describe planetary motion in terms of elliptical orbits, equal area in equal time, and the relation between the square of the orbit's period and the cube of the semi-major axis. These laws help explain the motion of planets without considering their masses and are fundamental in astronomy.
How does potential energy change with separation between two masses?
easyAnswer: The gravitational potential energy between two masses decreases as their separation increases, defined by the equation V = -G*(m1*m2)/r. As r approaches infinity, the potential energy approaches zero, indicating that the masses have minimal gravitational interaction at infinite separation.
How would the weight of an object change if it were taken to the moon?
easyAnswer: An object's weight on the moon would decrease because the moon's gravitational acceleration is about 1/6th that of Earth's. Therefore, an object would weigh 1/6th of its weight on Earth when measured on the moon.