Name_________________________

STUDENT INSTRUCTION AND ANSWER SHEET

Activity 1: Exploration-The Motion of the Sun

The four drawings below show the positions of the Sun and Jupiter at four different times during a single orbit. Since the Sun and Jupiter account for nearly all the mass of our solar system we will model our solar system as a two-body problem involving only the Sun and Jupiter.

A. Does the Sun appear to always remain in the same position? If not, describe its motion.

B. Estimate the time (in Earth years) for one orbit of the Sun (this time is known as the orbital period). How does this time compare to the orbital period of Jupiter?

C. In each diagram, find and label the locations of the center of the Sun's orbit and the center of Jupiter's orbit. If these two positions coincide with each other, the position is the Center of Mass (CM) for the system.

D. On each drawing of the Sun and Jupiter system, sketch a vector to represent the velocity of each orbiting object. What does the direction of the vector represent? What does the length of the vector represent? How does the length of the vector you drew for Jupiter compare to the length of the vector you for the Sun?

E. When studying motion it is useful to consider the object's velocity as being made of two components (or parts). The component of velocity that is directed toward (negative) or away (positive) from the observer's line of sight is known as the radial velocity. The component of velocity that is directed perpendicular to the observer's line of sight is known as the tangential velocity. Imagine that you are the observer shown in each of the drawings.

i. At which date(s) would the Sun appear to be moving with a radial velocity?

 

ii. At which date(s) would the Sun appear to be moving with a tangential velocity?

 

iii. At which date(s) would Jupiter appear to be moving with a radial velocity?

 

iv. At which date(s) would Jupiter appear to be moving with a tangential velocity?

 

F. What would you see in September 1992 from the position of the observer? Draw a sketch like those shown on the previous page. Include velocity vectors for the Sun and Jupiter.

i. From the location of the observer, does the Sun appear to be moving with a radial velocity, or with a tangential velocity, or both? Explain your reasoning.

 

ii. Does Jupiter appear to be moving with a radial velocity, or with a tangential velocity, or both? Explain your reasoning. Explain your reasoning.

 

G. Imagine that you are located at the observer location shown in each drawing and that there is a satellite located near the Sun on the side closest to you. If the satellite was sending out a distress signal:

i. At which date would the message arrive during the shortest interval of time?

 

ii. At which date would the signal take the greatest amount of time?

 

iii. During what time interval would the signal have a Doppler shift to a longer wavelength?

 

iv. During what time interval would the signal have a Doppler shift to a shorter wavelength?