Questions and Answers
What is gravitation?
The force in which the earth pulls the objects towards itself.
Every object in the universe attracts every other object.
True
What is the universal law of gravitation?
Every object in the universe is attracted to every other object by a force proportional to the product of their masses and inversely proportional to the distance between them.
The formula of the universal law of gravitation is G = _____
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What is the SI unit of the gravitational constant 'G'?
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What is the value of G?
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Gravitational force between small and big objects causes noticeable motion.
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How does gravitational force hold the solar system together?
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What is Kepler's first law?
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What does Kepler's Second Law state?
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What is Kepler's Third Law?
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What does Newton's third law imply in gravitation?
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What is free fall?
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The equations of motion for freely falling bodies are v = u + gt, h = ut + _____, v^2 = u^2 + 2gh.
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What is mass?
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What is weight?
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What is the weight of an object on the moon?
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Study Notes
Gravitation
- Gravitation is the force exerted by the Earth that pulls objects towards its center, acting downward and responsible for holding the atmosphere.
Universal Attraction
- Every object in the universe attracts every other object, regardless of size. Smaller masses result in gravitational forces that are often undetectable.
Universal Law of Gravitation
- This law states that the gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Gravitational Formula
- The formula for the universal law of gravitation is expressed as ( F = \frac{G \cdot m_1 \cdot m_2}{d^2} ).
SI Unit of Gravitational Force
- The SI unit of the gravitational constant ( G ) is ( \text{Nm}^2/\text{kg}^2 ).
Value of G
- The value of the gravitational constant ( G ) is approximately ( 6.67 \times 10^{-11} \text{Nm}^2/\text{kg}^2 ).
Gravitational Force Between Different Sizes
- Gravitational attraction exists between all objects, but the force is often too small to cause noticeable motion, especially between objects of vastly different sizes.
Solar System Dynamics
- The gravitational force between celestial bodies, such as the Sun and Earth, is significant due to their large masses, keeping planets in uniform circular motion around the Sun.
Kepler's First Law
- The orbit of a planet around the Sun is elliptical, with the Sun located at one of the foci of the ellipse.
Kepler's Second Law
- A line segment connecting a planet and the Sun sweeps out equal areas during equal intervals of time, indicating varying speeds; planets travel faster when closer to the Sun.
Kepler's Third Law
- The square of a planet's orbital period is proportional to the cube of the semi-major axis of its orbit, expressed as ( r^3 \propto T^2 ).
Newton's Third Law and Gravitation
- When a small mass, such as a stone, falls to Earth, it experiences significant acceleration due to gravity, illustrating the principles of Newton's third law.
Free Fall
- Free fall is the motion of an object falling under the sole influence of gravity, with no other forces acting on it.
Equations of Motion for Free Fall
- Key equations include:
- ( v = u + gt )
- ( h = ut + \frac{1}{2}gt^2 )
- ( v^2 = u^2 + 2gh )
Mass
- Mass is defined as the quantity of matter in a body, measured in kilograms, and is a scalar quantity. An object's mass cannot be zero.
Weight
- Weight is the force of gravity on an object, calculated as ( F = ma ), with 1 kg having a weight of approximately 9.8 newtons. Unlike mass, weight is a vector quantity.
Weight on the Moon
- The weight of an object on the Moon is roughly one-sixth of its weight on Earth, demonstrating how gravitational pull differs by celestial bodies.
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Description
This quiz covers essential concepts of gravitation for 9th-grade students. It includes definitions and principles introduced by Newton concerning the gravitational force and its impact on objects. Perfect for helping students review and understand gravity's role in the universe.