http://aspire.cosmic-ray.org/labs/tides/tides_main.html

PART 1: CRITICAL SPEED

GOAL: To find out how to get the earth to move in a circle around the sun.

Complete the activity as directed on the screen. Please answer the following questions:

1. What is the speed the earth needs to achieve circular orbit around the sun (ie. critical speed)?

2. What happens to the earth when the speed is GREATER than its critical speed?

3. What happens to the earth when its speed is LESS than its critical speed?

PART 2: GRAVITATIONAL FORCE

1. Looking at the diagram, which point on the Earth do you thing would have the greatest gravitational effect from the moon (A, B, C, D, or E)? ____________ Explain.

Graphing Data: Complete the tables with data based on the calculations on the computer.



1. Why is the gravitational force greater at A than E?

2. Also, notice the BIG difference in the gravitational force between the earth and the moon and the earth and the sun. The earth has a very strong gravitational attraction to the sun and a less powerful attraction to the moon. Why do you think the earth does not move in towards the sun?

3. Based on your observations from the data table and the graph, what factor in the gravity equation accounts for the change in gravitational force, G (gravity), m (mass of one object) ,m (mass of the other object) ,or r (distance between objects). Explain why.

Part 3

Hypothesize what would happen to the Earth-moon system in the following scenarios. Circle your answer

1. The mass of the moon increases

a. The gravitational attraction between the earth and the moon would (circle your choice):

Increase Decreases Nothing

b. The speed the moon needs to maintain orbit would (circle your choice):

Increase Decreases Nothing

2. If the mass of the earth decreases and the moon stays the same

a. The gravitational attraction between the earth and the moon would (circle your choice):

Increase Decreases Nothing

b. The speed the moon needs to maintain orbit would (circle your choice):

Increase Decreases Nothing

TIDE SIMULATOR:

Record the tide level in each box once you have it correct.

H = high tide M = medium tide L = low tide

We know there is a tidal effect between the earth and sun. We also know there is a tidal effect between the earth and the moon. We have calculated the gravitational force for the earth-sun system and the earth moon system.

Which system has the largest gravitational force?

Which system has the greatest tidal effect?

Based on your data and calculations, which hypothesis answers the following question. Circle your answer.

Why does the sun, which is much larger than the moon, have less of an effect on the Earth’s tides?

a) When mass increase gravity increases, but the tidal effect decreases

b) Tidal effect is not related to gravity

c) The moon is further away from the earth than the sun

d) For tidal effect, two objects located close together is more important the strength of gravitational force.

Explain.