# Objective: Explain Forces in Our Universe

Objective: Explain forces in our universe

Copy the following five terms in your science notebook:

Inertia – an object in motion stays in motion; an object at rest stays at rest

Momentum – indicates how hard it would be to stop an object, a product of mass x velocity

Gravity – force of attraction; pulls things together- depends on distance and mass

Mass – amount of matter in an object

Weight – the product of mass x gravity

Station 1:

Gravity’s Effect on Objects in Motion

Instructions:

• Hold the ruler so the top edge is 20cm above the table surface. Release the marble and observe it rolling down the ruler and into the sand box. Fill out table below.
• Repeat process at 25cm and 30cm above table surface.

Pre-experiment predictions:

What will happen when marble is released?

How will the time be affected as the ruler height is adjusted?

How will the distance the marble rolls on the sand change as the height of the ruler changes.

Do the experiment and complete the cart below

Height of marble ramp above table / Time (s) it takes for marble to HIT the sand / Distance Marble rolls across sand

Post experiment questions:

B: What pulling force acts on the marble at all times?

C: How does the forward speed of the marble affect the motion of the marble once it leaves the ruler?

D: All planets that orbit the sun are traveling due to inertia and falling toward the sun due to gravity. Describe the path of something that has forward motion (like your marble) but is also being pulled down by gravity. Draw this phenomenon!

Station 2:

Testing Balanced and Unbalanced Forces

A: Describe the motion of the marble when an unbalanced force (the tape ring) influences it.

B: Describe the motion of the marble when the unbalanced force is removed.

C: Suppose you lifted the ring when the clockwise orbiting marble was at the “1” Draw the path the marble would take.

D: Suppose you lifted the ring when the clockwise orbiting marble was at the “4” Draw the path the marble would take.

Station 3:

Use the laptop, calculator, and your research skills to find the momentum of 4 planets in our solar system.

Momentum = mass x velocity

Planet / Mass / Velocity / Momentum

Station 4:

Mission: Saturn, Uranus, and Neptune

-As you read list examples of gravity, inertia and momentum (think outside the box)

1. Which planet has the most gravity
1. Which planets have less gravity than Earth?
1. Which planets have more gravity than Earth?
1. Explain how a planet that is much larger than Earth, could have less gravity than Earth.

Station 5:

Planetary distance and orbit

Instructions:

You will carefully be swinging a “planet” attached to a piece of string at a various distances. Observe the speed of the “planet”, the time it takes to make TENrevolutions.

Pre-experiment prediction:

How will the time (s) that it takes for the planet to make 10 revolutions change as the distance increases?

DISTANCE (cm) / TIME (s)
10
20
30
40
50
60
70
80
90
100

Post experiment questions:

There is a piece of tape on the rope 90cm from the “planet” (ball), when swinging the planet at a distance of 100cm, which is moving faster; the ball or the piece of tape? Why?

Let’s pretend that the piece of tape is another ball or “planet” with the same mass as the ball at the end of the rope. Which ball or “planet” has more momentum? Why

Station 6:

Inertia in our Solar System

All the objects in our solar system spin in the same direction around the sun. Briefly read over the Formation of the solar system in the textbook and explain why the planets spin in the same direction. This should be a detailed paragraph!!! Include the word INERTIA in your answer

Station 7: