A spaceship approaches Earth with a speed 0.38c. A passenger in the spaceship measures his heartbeat as 72 beats per minute.
How many beats per minute are observed in the telemetry radio signals received on Earth? Note that, in addition to time dilation, one must take into account that the signals of successive heartbeats have to travel shorter distances because the spaceship is moving closer (Doppler Effect). A) 75
B) 107
C) 48
D) 100
E) 67
Question 2
Hydrogen emits light at certain discrete frequencies. One particular emission has a frequency of 4.57 1015 s-1, as measured in the frame of reference of the hydrogen atom.
Light from this emission is observed coming from a star that is moving away from Earth at 0.900c. What is the observed frequency? Note that, in addition to time dilation, one must take into account that successive wavefronts have to travel longer distances because the star is moving away (Doppler Effect). A) 1.99 1015 s-1
B) 7.62 1015 s-1
C) 1.99 1016 s-1
D) 1.05 1015 s-1
E) 0.90 1015 s-1
From space earth shows itself as a planet covered mostly by water.
The span of Homo sapiens sapiens’ time on earth
The chain of infection: preventative measures follow each link of the chain.
Speed of Earth
Benvenuto Cellini, Saltcellar: Neptune (Sea) and Tellus (Earth).
Earth 430 Million Years Ago