Gravity

Gravity

By Daisy Alejo

CATCH ME, I’M FALLING GRAVITY: A Force of Attraction

Force of Gravity Large objects have a greater gravity than smaller objects. Gravity or gravitational forces exist when one object attracts another. It is the natural force that causes things to fall toward the earth. It is a force, which we don’t think a lot about. It is gravity that holds things to the Earth’s surface and prevents things from floating off into the atmosphere.

Isaac Newton was one of the first scientists to write about this force. There is a story that Isaac Newton was sitting under an apple tree in his garden when an apple fell downwards onto his head. “Why didn’t it float up into the sky?” he thought. Isaac Newton realised that there is a strong force, which pulls things towards the Earth that is called gravity. We measure the force of gravity in units called Newton, named after Isaac Newton. When you jump up into the air, your energy pushes your body off the ground but the force of gravity pulls you back down again.

Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. The gravitational pull of the moon pulls the seas towards it, causing the ocean tides. Gravity creates stars and planets by pulling together the material from which they are made.

There is gravity on the moon but it is much weaker than Earth’s gravity. When the American astronauts landed on the moon in 1969, they could leap and jump higher and more easily than on the Earth because the pull of gravity was less strong. The effect of Earth’s gravity gets weaker further out into space. Astronauts feel this change as their spacecraft leaves the Earth’s atmosphere. Slowly and gradually, the pull of the Earth’s gravity becomes less strong and, as the spacecraft gets nearer to the moon’s gravity starts to be felt.

Invisible Forces of Gravity

Gravity is the mutual attraction of two bodies in the universe. Since gravity refers to an invisible force pulling matter together, there are many examples of gravity. Every single thing has gravity, including people. Some objects have much more gravity than others. The Earth, for example, has more gravity than people. This is why an object that falls is drawn to the Earth and returns to the Earth instead of being drawn to a person and flying at that person. Some examples of the force of gravity include:

→ The force that causes a ball you throw in the air to come down again.

→ The force that causes a glass you drop to fall to the floor.

→ The force that keeps the Earth and all of the planets in line in the proper position in their orbits around the sun. .

→The force that causes the moon to revolve around the Earth.

→The force that keeps Jupiter's moons located around the planet.

→The force that causes your drink to rest in the bottom of your glass instead of hovering near the top of your glass.

→The force that causes an apple to fall downward from an apple tree.

→ The force that keeps you walking on Earth instead of floating away into space.

→The force that causes a piece of paper that is blowing in the wind to eventually come back down to Earth.

→ The force that causes a lock of your hair to fall to the floor after it has been cut off.

→ The force that causes a rock to roll downhill.

→The force that keeps Jupiter's moons located around the planet.

→The force that causes your drink to rest in the bottom of your glass instead of hovering near the top of your glass.

→The force that causes an apple to fall downward from an apple tree.

→ The force that keeps you walking on Earth instead of floating away into space.

→The force that causes a piece of paper that is blowing in the wind to eventually come back down to Earth.

→ The force that causes a lock of your hair to fall to the floor after it has been cut off.

→ The force that causes a rock to roll downhill.

GRAVITATIONAL FORCE

The gravitational force is a force that attracts any two objects with mass. In fact, every object, including you, is pulling on every other object in the entire universe! This is called Newton's Universal Law of Gravitation. Some examples of the force of gravity include: The force that holds the gases in the sun. The force that causes a ball you throw in the air to come down again. The force that causes a car to coast downhill even when you aren't stepping on the gas. The gravitational force only acts between very, very massive objects. The gravitational force between an object and the earth is inversely related to the distance between the object's and the earth's center. The gravitational force between two objects is independent of the mass of the smaller of the two objects.

IMPORTANCE OF GRAVITATIONAL FORCE

→ The gravitational force is very important to keep the universe functioning. The planets revolve around the Sun because of the force of gravity Galaxies exist also due to gravitational force. It is the force of gravity that starts the nuclear fusion in stars. Stars exist due to gravitational force.

→ Gravity is very important to us. We could not live on Earth without it. The sun's gravity keeps Earth in orbit around it, keeping us at a comfortable distance to enjoy the sun's light and warmth. It holds down our atmosphere and the air we need to breath.

→ Gravity is very important to our everyday lives. Gravity also is important on a larger scale. It is the Sun's gravity that keeps the Earth in orbit around the Sun. Life on Earth needs the Sun's light and warmth to survive.

→ The more mass an object has, the greater its gravitational force. Because the sun's mass is so great, it exerts a large gravitational force on the planets. That's one reason why the planets orbit the sun.

→ The more mass an object has, the greater its gravitational force. Because the sun's mass is so great, it exerts a large gravitational force on the planets. That's one reason why the planets orbit the sun.

→ Gravitational force can be used in various ways. For instance falling water can produce electricity, and water falls because of gravity.

THE LAW OF UNIVERSAL GRAVITATION

Isaac Newton generalized his observation in something called the Law of Universal Gravitation. His law states: All objects in the universe attract each other through gravitational force.

The strength of the force of gravity between two objects depends on two factors:

1.Mass of the objects

2.Distance between the objects

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Gravitational force increases as mass increases

Gravitational force decreases as distance increases

MASS

Mass is a property of matter. The mass of an object is the same everywhere.

Mass can never be zero.​

Mass does not change according to location.​

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WEIGHT

Weight depends on the effect of gravity. Weight increases or decreases with higher or lower gravity.

​Weight can be zero if no gravity acts upon an object, as in space.​

Weight varies according to location.

Weight often is measured in newton, a unit of force

Mass is the same for all matter everywhere.

Weight changes with location in the universe.

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To find weight when you already know the mass, use the formula

weight = mass times gravitational acceleration.

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Remember that on the surface of the earth, gravitational acceleration is always 9.8 m/s2, so simply plug in the mass and multiply it by 9.8 to get the weight in newton.