Knowledge & Understanding 1. A Rocket passes by earth at a speed of 0.300c. If a person on the rocket takes 245 seconds to drink a cup of tea how long would the same event take according to an observer on earth 2. How fast should a particle be travelling relative to an experimenter in order to have a measured mass that is 20 times its rest mass? 1Communication 1. A rocket with a mass of 2 x 10 kg is accelerated to 1 x 10 m/s. Calculate its a) Kinetic energy using classical equation bj Kinetic energy Using the relativistic equation 2. A certain chemical reaction requires 13.8 Joules of thermal energy a) What mass gain does it represent b) Why would the chemist still believe in the law of conservation of mass? 2Thinking 1. The surface of sodium metal is exposed to electromagnetic radiation of wavelength 6.5 x 10-'m. This wavelength is the maximum for which photoelectrons are released. a) Calculate the threshold frequency b) Show that the work function energy of the metal is 1.9 ev. c) For a particular wavelength of incident light, sodium releases photoelectrons. State how the rate of release of photoelectrons changes when the intensity of light is doubled. 2. High speed electrons may be used to probe inside atomic nuclei. a) Calculate the de Broglie wavelength for a single electron which has a momentum of 2.3 x 10-19kgms-1. b) Explain how your wavelength would change for neutron of the same momentum c) Explain how your wavelength would change for an electron of half the momentum LUApplication 1. Monochromatic light of wavelength 632.8mm is generated by a helium-neon laser having power of 9.42mW. Evaluate the following: a) energy and momentum of each photon, b) The number of photons emitted per second, and c) speed of a hydrogen atom to have momentum equal to that of an emitted photon by the laser m=mass of a hydrogen atom= 1.67x10 2kg 2. If an electron in a hydrogen atom moves from n=6 to n=4 state, what is the wavelength of the emitted photon. In what region of the electromagnetic spectrum does it reside