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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