Physics: Newton's Law of Universal Gravitation

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Questions and Answers

What significant value was determined by Henry Cavendish's experiment?

The potential energy of a ball

The mass of the Moon

The gravitational constant G (correct)

The distance between Earth and the Moon

How did Cavendish measure the gravitational force in his experiment?

By observing the color change in the spheres

By calculating the weight of the spheres

Using a laser distance meter

Through the angle of rotation of a suspended rod (correct)

What is stored in the gravitational field itself when a ball is raised above the Earth?

Mass of the ball

Potential energy (correct)

Kinetic energy

Heat energy

Which concept did Newton struggle to explain regarding gravitational forces?

How masses interact without contact Signup and view all the answers

What correction was made to Newton's laws regarding their accuracy?

They were revised to include concepts of gravitational fields Signup and view all the answers

What is the mass needed at the sun's surface to create a gravitational force of 470 N?

1.7 kg Signup and view all the answers

How far apart must two ships be to exert a gravitational attraction of 1.0 x 10^-3 N on each other if their mass is 1.0 x 10^8 kg each?

2.1 x 10^6 m Signup and view all the answers

What is the gravitational force experienced by a 50.0 kg mass on Jupiter's surface?

530 N Signup and view all the answers

Which celestial body has the highest gravitational pull on a 66.5 kg person according to the given data?

Earth Signup and view all the answers

What formula is used to find the gravitational force between two masses?

F_g = G rac{m_1m_2}{r^2} Signup and view all the answers

What does the constant G represent in the gravitational force equation?

The constant of universal gravitation Signup and view all the answers

Why does the Earth not accelerate significantly towards a falling apple?

Earth's mass is very large, resulting in tiny acceleration Signup and view all the answers

How does the gravitational force affect the moon's orbit around the Earth?

It serves as the centripetal force for the moon's circular path Signup and view all the answers

According to Newton's third law of motion, what can be said about the gravitational forces between two masses?

They are equal and opposite Signup and view all the answers

In the equation for gravitational force, how does distance affect the force between two masses?

Force decreases as distance increases, squared Signup and view all the answers

Which of the following is true about gravitational force?

It exists between any two masses, regardless of size Signup and view all the answers

What is the role of gravitational force in everyday objects such as desks in a classroom?

It creates a strong attraction between them Signup and view all the answers

What is the correct mathematical representation of gravitational force?

FG = G * m1 * m2 / r2 Signup and view all the answers

What is the term for the mutual force of attraction between particles of matter?

Gravitational force Signup and view all the answers

How does Newton's law of universal gravitation explain planetary orbits?

It indicates that a centripetal force holds planets in orbit. Signup and view all the answers

What happens to a cannonball projected at just the right speed from a mountaintop?

It enters a circular orbit around the Earth. Signup and view all the answers

What role does gravitational force play in relation to falling objects?

It causes objects to accelerate towards Earth. Signup and view all the answers

Which of the following accurately describes what keeps satellites in orbit around Earth?

The gravitational force acting as a centripetal force. Signup and view all the answers

What would occur if the gravitational force between the Earth and the sun suddenly disappeared?

Earth would move in a straight line at a constant speed. Signup and view all the answers

In Newton's thought experiment, what effect does increasing the initial speed of a cannonball have?

It increases the horizontal distance traveled. Signup and view all the answers

How does the gravitational attraction between Earth and the moon affect the tides?

It results in predictable changes in sea levels. Signup and view all the answers

What keeps a satellite in orbit around a planet?

The gravitational attraction between the satellite and the planet. Signup and view all the answers

What happens to the gravitational force between two students sitting in a classroom?

It is negligible because of their small mass. Signup and view all the answers

What is the predicted weight of a 65.0 kg person on the surface of Saturn?

211.2 kg Signup and view all the answers

At what height above Earth's surface does the acceleration due to gravity become 6.5 m/s²?

Approximately 1,200 km Signup and view all the answers

What is the relationship between the newly discovered value of G and Earth's mass using its radius?

It allows calculation of Earth's mass using gravitational formulas. Signup and view all the answers

What causes high tides on Earth?

The gravitational force exerted by the moon Signup and view all the answers

How often do high tides occur at a specific coastal location?

Every 12 hours Signup and view all the answers

What phenomenon creates the outward bulges that cause tides?

Differential gravitational force exerted by the moon Signup and view all the answers

Why does the gravitational force of the moon create two high tides?

Earth's rotation causes it to move through both bulges Signup and view all the answers

Which factors, besides the moon, can influence tides?

Earth's tilt and rotation Signup and view all the answers

What is the relationship between the gravitational force and the distance from the moon?

Gravitational force decreases as distance increases Signup and view all the answers

Which of the following is NOT a factor affecting ocean tides?

The temperature of ocean water Signup and view all the answers

In the Bay of Fundy, how much does the water rise at high tide?

16 m Signup and view all the answers

Study Notes

Objectives

Newton's law of universal gravitation explains satellite and planetary orbits, falling objects, and ocean tides.
Application of Newton's law allows problem-solving related to gravitational force.

Key Term

Gravitational force: Attraction between matter particles.

Newton's Law of Universal Gravitation

Planets, including Earth, maintain nearly circular orbits around the sun due to gravitational force.
Gravitational force also causes falling objects, like an apple, to be pulled toward Earth.
Newton’s thought experiment illustrates how a cannonball can orbit Earth if projected correctly, analogous to satellite motion.
The gravitational force is a centripetal force that keeps objects in orbit.

Gravitational Force Equation

Gravitational force formula: F₍G₎ = G m₁m₂/r²
G = 6.673 x 10^-11 N*m²/kg², known as the constant of universal gravitation.
Gravitational force between two masses is influenced by their masses and the distance separating them.

Gravitational Force Characteristics

Gravitational attraction exists between all masses, regardless of size.
Earth and the moon exert equal and opposite gravitational forces, exemplifying Newton's third law.
Despite gravitational attraction between small masses (like desks), the force is negligible compared to Earth’s mass.
Earth's significantly larger mass results in imperceptible acceleration towards a falling object due to the inverse relationship between mass and acceleration.

Tidal Phenomena

Ocean tides result from the gravitational influence exerted by the moon on Earth.
High and low tides are caused by variations in gravitational force across Earth’s surface.
The sun’s gravitational force also contributes to tides but is less significant than the moon’s effect.

Cavendish Experiment

Henry Cavendish’s 1798 experiment measured gravitational force between masses, allowing the determination of G and Earth’s mass.
Used a setup of small and large spheres to measure the gravitational attraction influencing a light rod.

Gravity as a Field Force

Newton's laws did not explain the mechanism of gravity; field theory later clarified this by describing gravity as a field interaction.
A mass creates a gravitational field, and energy associated with gravitational interactions is stored within this field.

Sample Problem and Practice

Example provided on using the law of gravitation to determine mass required for a specific gravitational force.
Exercises designed to apply gravitational concepts and calculations related to celestial bodies and forces experienced on their surfaces.

Section Assesment

Key concepts include the reasons why satellites remain in orbit and the effects of gravitational forces in everyday contexts.
Analysis of weights in differing gravitational environments, reinforcing the principles of Newton's gravitational laws.

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Description

This quiz focuses on Section 2 of Newton's Law of Universal Gravitation. It covers the explanation of gravitational force, its role in satellite and planetary orbits, and its effect on falling objects and tides. You will also apply the law to solve various problems related to gravitational phenomena.