Download Modern Physics Homework

Modern Physics Homework
Due: Thursday Oct. 17
Note: One problem per page maximum. Each page should have your name. Each problem should be
worked out neatly with your final answer boxed!! Staple your work together before submitting it.
1.
The Apollo 11 spacecraft that landed on the moon in 1969 traveled there at a speed relative to the
earth at 1.08x104 m/s. To an observer on the earth, how much longer was the trip?
2.
An astronaut whose height on the earth is exactly 6.0 ft is lying parallel to the axis of the
spacecraft moving at 0.9c relative to the earth. What is his height as measured by an observer in
the same spacecraft? What is his height as measured by an observer on the earth?
3.
A woman leaves the earth in a spacecraft that makes a round trip to the nearest star, 4 light-years
distant at a speed of 0.9c. How much younger is she upon her return than her twin sister who
remained behind?
4.
At what speed does the kinetic energy of a particle equal its rest mass?
5.
What is the percentage increase in the mass of a proton accelerated to a kinetic energy of
500 MeV?
6.
Find the total energy of a neutron (Mo=0.940 GeV/c2) whose momentum is 1.20 GeV/c.
7.
Ultraviolet light of wavelength 350 nm and intensity 1.00 W/m2 is directed at a potassium surface
(work function 2.2 eV). a) Find the maximum kinetic energy of the photoelectrons. b) If 0.5
percent of the incident photons produce photoelectrons, how many photoelectrons are emitted per
second if the potassium surface has an area of 1.00 cm2?
8.
Find the shortest wavelength present in the radiation from an x-ray machine where electrons were
accelerated by a 50,000 V potential.
9.
X-rays of wavelength 10.0 pm are scattered from a target. a) Find the wavelength of the x-rays
scattered through 45 degrees. b) Find the maximum wavelength present in the scattered x-rays. c)
Find the maximum kinetic energy of the recoil electrons.
10.
You detect a 27.0 keV gamma ray photon. a) What is the linear momentum of the photon?
b) What is the wavelength of the gamma ray?
11.
You perform an experiment twenty three times and obtain the following results:
58, 61, 63, 68, 69, 71, 71, 72, 72, 74, 75, 76, 77, 78, 79, 79, 79, 80, 82, 82, 86, 91, 98.
a) Calculate the average value of your measurements.
b) Calculate the standard deviation for your measurements
c) Write a 95% confidence interval for your measurements