AST 248 Lecture 25: Lecture 25

• School: Stony Brook University
• Department: Astronomy
• Course: AST 248
• Professor: James Lattimer

Document Summary

Rocket formula: v = s*ln((mfuel+mpayload)/mpayload) v is the velocity of the spacecraft, which weighs (not including fuel) mpayload after using the amount of fuel mfuel. This implies that v/s cannot be very much larger than 1. The exhaust velocity s is determined by energy content of fuel s = sqrt(2efuel/mfuel) The time lapse between two events is relative, e. g. , the twin paradox. Two events happening in different locations that are simultaneous to one observer need not be simultaneous to another. The dimensions of an object as measured by one observer may be different than measured by another observer, e. g. , the ladder paradox. Each twin sees the other as moving and having a slower clock. However, the traveling twin undergoes an acceleration to change direction which destroys the symmetry. He has fewer clock ticks than his twin. A light is emitted from a source, reflected by a mirror, and detected by a detector.