1. Gravitation (Universal Force of Attraction)
Definition:
Gravitation is the universal force of attraction that acts between any two masses in the universe. It is described by Newton’s Law of Universal Gravitation and governs large-scale interactions like planetary motion.
Mathematical Representation:
Newton’s Law of Universal Gravitation states that the force between two masses is given by:
F = Gm1m2 / r2
Where:
- F = Gravitational force
- G = Universal gravitational constant
- m1 and m2 = Masses of two objects
- r = Distance between their centers
Examples of Gravitation:
- The Earth and the Moon attract each other due to gravitation.
- The Sun holds the planets in orbit due to its gravitational pull.
- Two objects placed near each other experience a weak attraction due to gravitation.
2. Gravity (A Specific Case of Gravitation)
Definition:
Gravity is the force that pulls objects toward the center of a celestial body (like Earth). It is a special case of gravitation where one of the masses is a large celestial body.
Mathematical Representation:
- Weight of an object due to gravity:
W = mg
Where:
- W = weight (force due to gravity)
- m = mass of the object
- g = acceleration due to gravity (9.8 m/s2 on Earth)
- Acceleration due to gravity on any planet:
g = GM/R2
Where:
- g = acceleration due to gravity
- M = mass of the celestial body
- R = radius of the celestial body
Examples of Gravity:
- A ball falls to the ground when dropped.
- The Moon stays in orbit around Earth due to Earth’s gravity.
- An astronaut weighs less on the Moon because the Moon’s gravity is weaker than Earth’s.
Key Differences Between Gravitation and Gravity
| Feature | Gravitation | Gravity |
|---|---|---|
| Definition | The universal force of attraction between any two masses | The force exerted by a celestial body (like Earth) on objects near its surface |
| Scope | Acts between any two masses in the universe | Acts specifically between a planet (or celestial body) and nearby objects |
| Nature | Exists between any two objects with mass | Specific to Earth (or another planet/moon) pulling objects toward it |
| Force Equation | F = Gm1m2 / r2 | W=mg |
| Effect on Objects | Keeps planets in orbit, holds galaxies together | Keeps objects on Earth’s surface, causes falling objects |
| Acceleration | Not directly defined | Acceleration due to gravity on Earth is 9.8 m/s29.8 \, m/s^29.8m/s2 |
| Examples | The force between the Earth and the Sun | A person jumping and coming back to the ground |
FAQs on Gravitation and Gravity
Question 1: Is Gravitation a Repelling or Attractive Force?
Answer: The gravitational force is purely attractive in both theories, according to Newton’s General Theory of Relativity. However, the quantization of gravity demonstrates that gravitational force can also be repulsive.
Question 2: Why do we feel lighter on the equator than we do at the North Pole?
Answer: It’s because, in the equator, there’s more centrifugal force to counteract gravity’s effect. As a result, the equator has a lower overall weight than the poles.
Question 3: What are the methods used by spaceships to create artificial gravity?
Answer: Because of its spin around its axis, a starship can produce artificial gravity. A ship can also generate artificial gravity by constantly moving forward.
Question 4: What is free fall?
Answer: Any object that falls freely under the influence of Gravity is called the state of free fall.
MCQs on Gravitation and Gravity
Question 1: What is the nature of gravitational force?
A. Always repulsive
B. Always attractive
C. Can be both attractive and repulsive
D. Neither attractive nor repulsive
Correct Answer: B. Always attractive
Explanation: According to Newton’s law of universal gravitation, gravity is always an attractive force.
Question 2: What is the value of acceleration due to gravity on Earth?
A. 7.8 m/s²
B. 8.9 m/s²
C. 9.8 m/s²
D. 10.8 m/s²
Correct Answer: C. 9.8 m/s²
Explanation: The acceleration due to gravity on Earth is approximately 9.8 m/s².
Question 3: What happens to the gravitational force if the distance between two masses is doubled?
A. It becomes half
B. It becomes one-fourth
C. It remains the same
D. It doubles
Correct Answer: B. It becomes one-fourth
Explanation: According to Newton’s law of gravitation, force is inversely proportional to the square of the distance between the objects.
Question 4: Where is the gravitational force zero on Earth?
A. At the equator
B. At the North Pole
C. At the center of the Earth
D. At sea level
Correct Answer: C. At the center of the Earth
Explanation: Gravitational force is zero at the center of the Earth because the mass distribution exerts equal force in all directions.
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Conclusion:
- Gravitation is the general force that acts between any two masses.
- Gravity is a specific case of gravitation where a celestial body attracts objects toward it.
- Without gravitation, planets wouldn’t orbit the Sun, and without gravity, we wouldn’t stay on Earth! 🚀
