Question

George and Nancy are passing each other on the highway. George is travelling at 100 m/s. Nancy is travelling at 75 ms. a) How fast does George perceive Nancy to be travelling? b) How fast does Nancy perceive George to be travelling? Jane and Sam are passing each other in their spaceships. Jane is travelling at 0.8c. Sam is travelling at 0.7c. c) How fast does Jane perceive Sam to be travelling? (Circle one choice below.) Less than 0.70 0.70 0.80 Greater than 0.70 but less than 0.802 Greater than 0.8cc but less than ce d) How fast does Sam perceive Jane to be travelling? (Circle one choice below.) Less than 0.7c 0.70 0.80 Greater than 0.70 but less than 0.80 Greater than 0.8c but less than ce e) If Jane was to shine a flashlight toward Sam how fast would the light be travelling according to Sam? f) Imagine that the two ships pass by one another. The distance between the two ships is now increasing. If Jane was to shine a flashlight toward Sam's receding ship, how fast would the light be travelling according to Sam? g) Is there any direction or speed that Jane could travel such that the light from the flashlight in her ship would appear to Sam to be moving at a speed of greater than the speed of light? Explain your reasoning

Answer 1

€ speed of Nancy perceeved by George a velocity of Nancy uw - 75 m/s "O " George Van 100 nuts so po velocity of Nancy in Georges frame. 1. Warna UN-va = -75-100 ^2-175 so, for George Nancy is travelling at speed [ 175 m/s 22 towards left - velocity of George seen by Nancy, VAN? Va-w? 100-(-751.1175 m/s ] for speeds comparable to speed of light, we need to take into account relativistic effect so, velocity of same for cieved by Jane will be Usi Us Vy -0.76-0.86 ON T U U T- 60.78XO.SS) . -d15c 10.96cm 1+0.56 . i o.arc towards left @ Ans: Greater than 0.80 byt less than a @ For Sam, Vocea Ug-Us 0.8c-60-70) i vj Us - 9.8 cxo. 7 Elise 0.91 e - Ans: Greater than 0.8c len than @ speed of light will be c ( we can the the at one formula . C-(-0.76) си w . C CI+0.7) Ito.7 1 - -Cx0.78

© speed of light pube for sam will again be a I No. speed of light will always be c.