Gravitational Forces

​Introduction to Gravitational Force

​Standard

​Obtain, analyze, and communicate evidence to support an explanation that the gravitational force on an object is directed towards the planet's center.

​OBJECTIVE

​Understand the concept of gravitational force and its effects on objects.

Identify the central idea that gravitational force is directed toward the planet's center.

Multiple Choice

Explain the concept of gravitational force and its primary effect on objects. Select the most accurate statement from the following options.

• Gravitational force pushes objects upwards.

• Gravitational force pulls objects towards the planet's surface.

• Gravitational force causes objects to rotate.

• Gravitational force repels objects away from the Earth.

Multiple Choice

Describe how the direction of gravitational force changes as an object falls freely towards the Earth's surface. Choose the best description from the following options.

• Gravitational force acts sideways.

• Gravitational force is diagonal.

• Gravitational force remains the same.

• Gravitational force acts downward.

Multiple Choice

Provide a brief overview of Sir Isaac Newton's contribution to our understanding of gravitational force. Choose the most appropriate statement from the options below.

• Newton discovered the electromagnetic force.

• Newton proposed that gravitational force doesn't exist.

• Newton described gravitational force as the force of attraction between objects with mass.

• D) Newton invented the concept of frictional force.

Multiple Choice

If you were on a planet with half the mass of Earth but the same radius, how would the gravitational force compare to that on Earth? Explain your answer using one of the options below.

• Gravitational force would be weaker.

• Gravitational force would be stronger.

• Gravitational force would be the same.

• Gravitational force would depend on the object's shape.

Multiple Choice

Describe the relationship between the distance separating two objects and the strength of the gravitational force between them. Choose the most accurate description from the following options.

• The force decreases with increasing distance.

• The force increases with increasing distance.

• The force remains constant regardless of distance.

• The force becomes zero at a certain distance.

Multiple Choice

If you were inside a spacecraft traveling far from any celestial body, what would you experience in terms of gravitational force? Explain your answer with one of the options below.

• You would experience zero gravitational force.

• You would experience stronger gravitational force than on Earth.

• You would experience weaker gravitational force than on Earth.

• You would experience the same gravitational force as on Earth.

Multiple Choice

If you were inside a spacecraft traveling far from any celestial body, what would you experience in terms of gravitational force? Explain your answer with one of the options below.

• Zero gravitational force

• Stronger gravitational force than on Earth

• Weaker gravitational force than on Earth

• The same gravitational force as on Earth

Multiple Choice

Discuss what primarily determines an object's weight when it's on the surface of a planet. Choose the best option from the following.

• The object's volume determines its weight.

• The object's color determines its weight.

• The object's mass determines its weight.

• The object's shape determines its weight.

Multiple Choice

What is the acceleration due to gravity when an object is in free fall on Earth? Provide a brief explanation using one of the options below.

• The acceleration due to gravity is 1 m/s².

• The acceleration due to gravity is 5 m/s².

• The acceleration due to gravity is 9.8 m/s².

• The acceleration due to gravity is 20 m/s².

Multiple Choice

Explain the central idea regarding the direction of gravitational force. Select the most appropriate description from the options below.

• Gravitational force is directed away from the planet's center.

• Gravitational force is directed tangentially to the planet's surface.

• Gravitational force is directed toward the planet's center.

• Gravitational force is directed outward from the planet's core.

Multiple Choice

If an object is placed precisely at the center of the Earth, what would be the net gravitational force acting on it? Explain your answer with one of the options below.

• The net gravitational force would be zero.

• The net gravitational force would be weaker than on the surface.

• The net gravitational force would be stronger than on the surface.

• The net gravitational force would vary depending on the object's composition.

Mass…What is it?
---Mass is how much matter is in an object.
---In other words it is how much "stuff" is in an object
---Everything that is made of matter has mass.
---So anything that is a solid, liquid, gas, or plasma has mass.

Mass…How is it measured?
---We measure mass with a triple-beam balance or an electric
balance (there are various kinds)
--We are measuring the amount of matter in the object

5.E2U1.8

Mass and Weight
Notes

Science

-unit of measure for mass: Grams

-examples: milligrams (mg), grams (g), kilograms (kg)

Multiple Choice

What is mass?

• The force of gravity acting on an object

• The amount of space an object occupies

• The amount of matter in an object

• The resistance of an object to acceleration

Multiple Choice

Which unit of measurement is commonly used for expressing mass in the International System of Units (SI)?

• Pounds (lb)

• Kilograms (kg)

• Liters (L)

• Newtons (N)

Multiple Choice

If you have two identical objects, one made of lead and the other made of feathers, which object has a greater mass?

• The object made of lead

• The object made of feathers

• They have the same mass

• It depends on the volume of the objects

Multiple Choice

What happens to the mass of an object when it is divided into smaller pieces?

• The mass increases

• The mass decreases

• The mass remains the same

• The mass becomes zero

Multiple Choice

On a different planet, you find that an object has the same mass as it does on Earth. What can you conclude about the object's mass?

• The object is made of a different material

• The object's mass has changed

• The object's mass is constant regardless of the planet

• The object's mass is affected by the planet's size

Weight…What is it?
---Weight is the measure of gravity's pull on an object.
---In other words it is how "heavy" something feels
---Everything that is made of matter has weight.
---So anything that is a solid, liquid, gas, or plasma has weight.

5.E2U1.8

Mass and Weight
Notes

Science

Weight…How is it measured?
---We measure weight by using a scale (there are various kinds)
---We are actually measuring the force of gravity's pull

-unit of measure for weight: Newtons (not pounds!)

Multiple Choice

What is weight?

• The amount of matter in an object

• The force of gravity acting on an object

• The volume of an object

• The resistance of an object to acceleration

Multiple Choice

How does weight differ from mass?

• Weight depends on the amount of matter in an object, while mass depends on the force of gravity.

• Mass is the amount of matter in an object, while weight is the force of gravity acting on it.

• Weight and mass are the same thing and can be used interchangeably.

• Weight depends on the volume of an object, while mass depends on its shape.

Mass…How Can I Tell the Difference Between Mass & Weight?
---Mass does not change from planet to planet like weight does
Example:
-A full/unopened can of coke on Earth has a mass of 390g.
-The same unopened can on Mars would have the same mass (390g)
Example:
-A full/unopened can of coke on Earth weighs 3.61 Newtons.
-The same unopened can on Mars would weigh 1.20 Newtons
Why? Mars is smaller (less mass) than Earth & therefore has less gravity

5.E2U1.8

Mass and Weight
Notes

Science

Earth

Mars

Earth

Mars

Mass
390g

Mass
390g
weight
3.61 N

weight
1.20 N

Mass and Weight Video- Brain Break
---Watch this song-video, and have a dance party!
Link: "The Mass vs Weight Song" by Mr. Edmonds

5.E2U1.8

Mass and Weight

Dance
Party

Brain
Break

Mass and Weight Are

Not the Same!!!

Gravity
 is a “mysterious” force found everywhere in the universe
that pulls particles of matter together
Key Concept: Gravity is a pulling force (not a pushing force)

Law of Universal Gravitation
F.Y.I -Isaac Newton is credited with defining this law
The law states that gravity is everywhere in our universe, and
that its attractive force changes based on mass and distance.

Reminder: Mass is the amount of matter in an object

Summary: Every particle of matter is attracted to every other
particle of matter.

5.E2U1.8

Gravity-Mass and Distance
Notes
Science

Mass Affects Gravity


Objects with more mass have stronger gravity



Look below: (bowling ball and a baseball) both objects are
made of matter, so both objects have gravity.



So both objects are being pulled towards each other.



Yet the ball with more mass (bowling ball) has more gravity.



Therefore its pull is stronger (view animation)

Diagram 01

(Imagine these objects are floating in space)

Mass Affects Gravity


The example of a bowling ball and a baseball is similar to the
gravity effect with a planet and a moon

Earth and the Moon

Diagram 01

Diagram 02

(Imagine these objects are floating in space)

Notes

5.E2U1.8

Gravity-Mass and Distance
Science

Mass Affects Gravity


Look below: (baseball and a golf ball) both objects are made
of matter, so both objects have gravity.



So both objects are being pulled towards each other.



Yet the ball with more mass (baseball) has more gravity.



Therefore its pull is stronger (view animation)



This is similar to the gravity effect with a moon and a asteroid

Notice the volume (size) of the Sun contrasted with Jupiter

 The Sun is bigger because it has more matter (mass)
 Because it has more mass, it likewise has more gravity

Note: The planets are not

actually this close to the Sun

Jupiter has more mass than Earth.

Therefore Jupiter has more gravity than Earth.

The Earth has more mass than the Moon.

Therefore Earth has more gravity than the Moon.

Jupiter

The Moon

Earth

Earth

Distance Affects Gravity


Affect of gravity increases when objects are closer together.



Affect of gravity decreases when objects are farther apart.

In diagram 01 the two soccer balls are 5m apart (floating in space).
In diagram 02 the two soccer balls are 10m apart (floating in space.

Notes

Gravitation attraction is greatest when they are closer together.

5.E2U1.8

Gravity-Mass and Distance
Science

10 meters

Diagram 02

5 meters

Diagram 01

The Moon

Earth

The Sun

Distance Affects Gravity

5.E2U1.8

Gravity-Mass and Distance



So the Moon’s gravitation pull on Earth’s oceans
(tides) is greater than the Sun’s gravitation pull.



The Sun has more gravity than the Moon.



Yet the Moon is closer to Earth than the Sun.

Gravity and the Theory of Relativity
F.Y.I. -Einstein theorized that mass warps (bends/curves)
space and this warping explains the force we call gravity.

Watch both of these Youtube videos:
Write down three things that catch your attention, and be
ready to share afterwards.
(1) Link: Curvature of Space-Time (34 sec)
(2) Link: How Gravity Really Works (1 min 45 sec)