Lecture 25 Relativity byexamples
Lecture 25 Relativity by examples 1
Systems of Inertial Coordinates? Each coordinate system has x, y, z axis plus a clock.Every clock is the same ideal clock
Systems of Inertial Coordinates • Each coordinate system has x, y, z axis plus a clock. • Every clock is the same ideal clock. 2
Simultaneous is relative? Consider a train moving with a speed u,. The suppose the length of the car is L, the light willtravel with speed c, the light simultaneously reachboth the end of the car at time, L/c. However, for someone on the ground, this is nottrue..In this clock..3
Simultaneous is relative • Consider a train moving with a speed u, • The suppose the length of the car is L, the light will travel with speed c, the light simultaneously reach both the end of the car at time, L/c • However, for someone on the ground, this is not true. • In this clock. 3
Life time of muon·Muon is a particle unstable.. Muon will decay due to weak interactions, withhalf-life 2.2x10-6 sμ+ →e++Ve+ Vu? However, a high-energy muon will live muchlonger!· Average energy of muon on the grand is 4GeV/c?the mass of muon is 105.7MeV/c2, thus the y factoris about 37. Thus the muon live about 37 timeslonger. (travel 2.2x37X1000x30cm = 24km!)1
Life time of muon • Muon is a particle unstable. • Muon will decay due to weak interactions, with half-life 2.2x10-6 s 𝜇 + → 𝑒 + + 𝜈𝑒 + 𝜈𝜇 • However, a high-energy muon will live much longer! • Average energy of muon on the grand is 4GeV/c2 , the mass of muon is 105.7MeV/c2 , thus the 𝛾 factor is about 37. Thus the muon live about 37 times longer. (travel 2.2x37X1000x30cm = 24km!) 4
Measuring the length of a ruler.Twoevents.. First events when the ruler is at the first end·Second events.5
Measuring the length of a ruler • Two events. • First events when the ruler is at the first end. • Second events. 5