Key Questions Save your answers to the Key Questions. When you have completed the unit, submit them to ILC for marking. (22 marks) 58. The proper length of spaceship A is 60.0 m and the proper length of spaceship B is 120.0 m. The proper mass of spaceship A is 15 000 kg. An observer on earth watches the two spaceships fly past at a constant speed and determines that they have the same length. If the speed of the slower spaceship is 0.70c, find a) the length of spaceship A, relative to an observer on earth. (3 marks) b) the speed of spaceship B, relative to an observer on earth. (3 marks) c) the mass of spaceship A, relative to an observer on earth. (3 marks) 59. A nuclear power generating station generates 3.00 x 10' W of power. How much mass does the plant convert into energy in one month (30 days)? Assume that the process is 100% efficient. (5 marks) 60. a) Calculate the kinetic energy required to accelerate a single proton from a rest position to 0.9999c. The mass of a proton is 1.67 x 10" kg. (4 marks) b) Find the ratio of the kinetic energy to the energy of a proton at rest. (3 marks) c) Explain why no particle accelerator will ever be able to accelerate any particle to the speed of light. (1 mark)a) the maximum kinetic energy of the emitted electrons. (4 marks) b) the cutoff potential required to stop the photoelectrons. (2 marks) 63. Use Max Planck's quantum theory to explain the following behaviour of photoelectrons. a) Low-intensity light does not release any photoelectrons. What will happen if the light is made brighter? Explain your reasoning. (2 marks) b) Low-intensity light releases photoelectrons. What will happen if the light is made brighter? Explain your reasoning. (2 marks) c) Low-intensity light does not release any photoelectrons. What will happen if the frequency of the light is gradually increased? Explain your reasoning. (2 marks) Now go on to Lesson 20. Do not submit your coursework to ILC until you have completed Unit 5 (Lessons 17 to 20)