# data[].attributes.body
Interactive tool to demonstrate Doppler effect and Doppler frequency:
http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::800::600::/sites/dl/free/0072482621/78778/Doppler_Nav.swf::Doppler%20Shift%20Interactive

Question from the interactive tool:

(1) What's observer frequency and source frequency?

(2) If both the spaceship (observer) and the planet station (source) are stationary, the radio frequency sent by the planet station is 1 GHz, what's the signal frequency received by the spaceship?

(3) If the spaceship is stationary, the planet station is moving towards the spaceship, how does the observer frequency change? How if the planet station is moving away from the spaceship?

(4) The Doppler frequency equation is given below. If the spaceship is stationary, the planet station is moving towards the spaceship at the speed of 10,000 m/s, the frequency of the radio sent from the planet station is 1 GHz, calculate the radio frequency received by the spaceship.

Group Discussion (5) - (9):
(5) If the planet station is stationary and sending an SOS signal at the frequency of 2 GHz, while the spaceship is flying away from it at the speed of 18,000 m/s, what's the SOS signal frequency will be monitored by the spaceship?

(6) If the spaceship is towards the planet station at the speed of 10,000 m/s while the planet is moving away from the spaceship at the speed of 1,000 m/s, the planet station is sending a radio signal with the frequency of 100 MHz, what's the radio frequency picked up by the spaceship?

(7) The spaceship and the planet are approaching each other at the same speed of 2 km/s, while the planet station is sending a signal at the frequency of 10 kHz, what's the signal frequency received by the spaceship?

(8) If the spaceship and the planet are agreed on the frequency of 1 GHz when sending signals to each other. One day the spaceship receives a signal of 0.99998 GHz from the planet station when the spaceship is stationary. What's the speed and direction of the planet movement?

(9) Assuming the distance between the spaceship and the planet is 1000 km at the beginning, the Star Omega is at the 1000 km north to the spaceship. The planet station starts to move towards the Star Omega at the speed of 2 km/s and sending a signal at the frequency of 1 GHz, the spaceship is stationary, what's the signal frequency when it arrives the spaceship?

# data[].attributes.body
https://padlet.com/chrisyang/EN0017Week3

# data[].attributes.body
Exercise: