MOTION IN THE SOLAR SYSTEM

ENGAGE, EXPLORE, EXPLAIN

ENGAGETHE ATTRACTION TANGO

THE ATTRACTION TANGO

• In your science journal, on the next clean page, title the page with “The Attraction Tango.”

• In your group, one person take a ping pong ball and roll it across the table to another person. In your science journal, describe what forces are acting on the rolling ping pong ball.

• As a class, observe your teacher’s demonstration of the ping pong ball on a string. Draw a picture in your science notebook of the forward motion and gravitational force.

• As a group, make a prediction of what would happen if the teacher let go of the string.

• Answer the following questions in your science notebook:

• What does the model tell us about the effect of gravity of the orbit of a body in motion around the Sun?

• What will happen to the ball when it is released from its circular movement? Why?

EXPLOREBACKGROUND INFORMATION

ORBITS

• All celestial bodies in the Solar System move in predictable patterns known as orbits.

• Orbits are controlled by gravity.

GRAVITY

• Gravity is the force of attraction between two or more masses.

• Everything has gravity.

• The more mass, the stronger the pull.

THE SUN

Since the sun is the most massive object (think all the planets combined), it governs the motion of all other bodies in the solar system with its gravity.

Bodies remain in orbit due to the balance between gravitational forces and the constant forward motion of the celestial bodies.

MOMENTUM

• The constant forward motion.

• You can gain or lose momentum.

• Momentum is a unit of measurement, such as kilogram per second.

INERTIA

• Natural resistance of an object to change its acceleration and momentum

• Can not be gained or lost

WHY IS INERTIA IMPORTANT?

A celestial body in orbit has inertia (the property to resist change in motion).

Momentum measures inertia.

So, theoretically, this means if the Sun’s gravitational pull suddenly stopped, Earth’s inertia (momentum) would make the planet continue in a straight line out into space rather than continue in an orbital path.

DISTANCE AFFECTS GRAVITY

Gravitational attraction not only depends on the mass of the objects involved but also the distance between the two objects.

As distance between objects increase, gravity decreases.

Since the Sun has 99.87% of all the mass in the Solar System, it has the strongest gravitational force. The gravitational field is able to attract all of the objects within the Solar System.

EXPLORE ACTIVITYPART I: BIG, BIGGER, BIGGEST

NEWTON’S UNIVERSAL LAW OF GRAVITATION

Sir Isaac Newton: English mathematician, astronomer, and physicist (described in his own day as a "natural philosopher") who is widely recognized as one of the most influential scientists of all time and a key figure in the scientific revolution.

NEWTON’S UNIVERSAL LAW OF GRAVITATION

• Two objects in the universe exert gravitational attraction on each other in a universal manner.

• Every object in the universe attracts every other object with a force that is directly related to the mass of the objects and inversely related to the distance between the objects.

• So…

• Direct Relationship: the greater the mass of the objects, the greater the force of gravity; the smaller the mass of the objects, the smaller the force of gravity

• Inverse relationship: the greater the distance between the objects, the smaller the force of gravity; the smaller the distance between the objects, the greater the force of gravity

• This is true for all objects in the universe, not just planets, stars, and moons.

BIG, BIGGER, BIGGEST

Draw this table in your journalGravitational

ForceCelestial Object

1.

2.

3.

4.

5.

6.

7.

8.9.

10.

Solar System Objects

most

least

ANSWER THE FOLLOWING QUESTIONS

1.What is the largest object in our solar system?

2.Why does this object have the most gravitational pull?

3.How many objects have more gravitational pull than Earth? Explain.

4. If Earth’s Moon was added to this ranking, where do you think it would fit?

EXPLORE ACTIVITYPART II: HOW FAR IS TOO FAR?

BACKGROUND

The universal law of gravitation applies to all objects in the universe (although some gravitational interactions are so small they are not noticed). It would be difficult to measure small gravitational interactions. Magnetism, like gravity, has an inverse relationship between distance and force attraction. Magnets can be used in the classroom to model the force of gravitational attraction. In this experiment, you will test the relationship between distance and the strength of magnetic force to model that of gravitational force.

RELATIONSHIP BETWEEN OBJECTS

Questions:1. What is Newton’s

universal law of gravitation?

2. Why are magnets used to investigate gravity?

EXPLORE PART IV: PLAN YOUR MODEL

PLANNING

You will now develop a model to test the relationship between distance and the strength of the force of gravity. Since the force of gravity between two masses is difficult to observe in a classroom and magnetic force has the same relationship between distance and strength, you will use magnets to observe magnetic force as a substitute of the relationship between distance and the strength of gravitational force.

Question of Inquiry:With your class, discuss the question of inquiry and list the materials you will need to conduct your investigation.

IN YOUR JOURNAL ANSWER THE FOLLOWING QUESTIONS

1. My question of inquiry:

2. The hypothesis:

3. What is the independent variable (also known as the manipulated variable)?

4. What is the dependent variable (also known as the responding variable)?

5. What materials, equipment, and technology will be need for this model?

6. List all safety precautions that must be taken.

7. Copy the data chart to the right in your journal.

EXPLOREPART V: IMPLEMENT YOUR MODEL

PROCEDURE

ANALYZE DATA

1. What occurred to the distance between the paper clip and magnet as the pieces of cardboard

were added to the setup?

2. What effect did adding the pieces of cardboard have on the force of attraction?

3. How was the attraction of the paper clip to the magnet affected by the increase in distance

between the paper clip and the magnet?

ANALYZE DATA4. If the magnet represents an object exerting the force of gravity and the paper clip represents

an object being pulled by the gravity, what effect does distance have on the strength of the

force?

5. How are models with magnets a good way to investigate gravitational force?

6. What are the limitations of using magnets to investigate gravitational force?

7. How does this model relate to our solar system? Give an example.

REFLECTIONS AND CONCLUSIONS

1. Is the hypothesis supported by the data? Explain.

2. How did the results reveal a relationship between the independent and dependent variables?

3. Where could errors have been made while collecting or organizing data?

4. What do you conclude about this model?

5. What would you do differently if you were to conduct this experiment again?

EXPLAINCOMPARING OBJECTS IN THE SOLAR SYSTEM

MOVEMENT

As you are sitting and reading this, are you moving?

Absolutely! Every organism , building, and structure on Earth is always moving. How fast?

Just to be able to make one full rotation on Earth’s axis, we are all continually moving at almost 1,600 kilometers per hour! That’s roughly 1,000 miles per hour!

MOVEMENT

In addition to rotating everyday, Earth is also constantly in motion while orbiting the Sun. An orbital path is the gravitational curved path of an object around a point in space. How long does it take to make one revolution around the Sun? Roughly 365 days, or one year.

ORBITS IN THE SOLAR SYSTEM

The model in the picture works to illustrate the differences in each planet’s orbit. The closer the planet is to the Sun, the shorter one revolution is. Similarly, the farther the planet is from the Sun, the longer the revolution.

HOW FAST IS EARTH’S ORBIT?

Earth completes its 93-million mile journey around the Sun every year.

That means the Earth covers 18.5 miles every second.

So, we are currently zooming around the Sun at 66,600 miles per hour!

GRAVITY

Gravity is the force that causes objects with mass to attract one another. The larger object is able to exert more gravity on the smaller object. For example, we are pulled to Earth’s surface because Earth has a larger mass than we do.

The Sun is so massive that its gravity pulls all the objects in the solar system toward it.

INERTIA

Inertia is the tendency of a physical object to remain still or continue moving, unless force is applied. Since the planets are already moving along their orbital paths, it would take an incredible amount of force to stop them or to knock them out of orbit.

IS THE SUN THE ONLY THING IN THE SOLAR SYSTEM THAT HOLDS OTHERS IN ORBIT?

While Earth orbits the Sun, the Moon orbits Earth. Once again, the object with less mass (the Moon) orbits the object with the larger mass (the Earth). The orbiting of the Moon around Earth gives us the Lunar Phases. We will talk about that later…

WHAT DO YOU THINK?

In your science journal:

1. Draw the Sun, Earth, and Moon. Construct a model of the interaction of gravity and inertia by drawing dashed lines to demonstrate the gravity celestial objects display on each other.