page 05 6. A spacecraft is travelling at 0·10c relative to a star. An observer on the spacecraft measures the speed of light emitted by the star to be A 0·90c B 0·99c C 1·00c D 1·01c E 1·10c. 7. A spacecraft is travelling at a speed of 0·200c relative to the Earth. The spacecraft emits a signal for 20·0 seconds as measured in the frame of reference of the spacecraft. An observer on Earth measures the duration of the signal as A 19·2 s B 19·6 s C 20·0 s D 20·4 s E 20·8 s. 8. How many types of quark are there? A 8 B 6 C 4 D 3 E 2 9. An electron is a A boson B hadron C baryon D meson E lepton. [Turn over