Question 18.01: The length of a space ship is measure to be exactly one-third of its proper length. What is the speed of the space ship relative to the observer?

Question 18.02: The time period of a pendulum is measured to be 3s in inertial frame of the pendulum. What is the period when measured by an observer moving with a speed of 0.95c with respect to the pendulum?

Question 18.03: An electron, which has a mass 9.11×10^-31 kg, moves with a speed of 0.75c. Find its relativistic momentum and compare, this value with the momentum calculated from classical expression.

Question 18.04: An electron moves with a speed of v=0.85c. Find its total energy and K.E in electron volt.

Question 18.05: The rest mass of a proton is 1.673×10^-27 kg. At what speed would the mass of the proton be tripled?

Question 18.06: At what fraction of speed of light must a particle move so that its K.E is one and a half times its rest energy?

Question 18.07: A metal, whose work function is 3.0 eV, is illuminated by light of wavelength 3×10^-7m. Calculate (a) The threshold frequency, (b) The maximum energy of photoelectrons (c) The stopping potential.

Question 18.08: The thermal radiation from the sun peaks in the visible part of the spectrum. Estimate the temperature of the sun.

Question 18.09: A 50 k eV X-ray is scattered through an angle of 90˚. What is the energy of the X-ray after Compton scattering?

Question 18.10: Calculate the wavelength of de-Broglie waves associated with electrons accelerated through a potential difference of 200 V.