Department of Physics
RUSMART pages (weather)
Spring 2013 Classes & Info
My daily schedule
NSF REU Program (list of REU sites)
The Nucleus (resources for
pics from the north pole trip
the picture from the trip
Simple 2-liter water rocket
American Institute of Physics
Homework #1: due Friday February 1 by 5:00:00pm
That's all for homework #1.
- problem 1.35. This is a simple use of the old physics-2 expression for the electric force, F=kq1q2/r2, with k=1/(4πε0)=8.99x109N⋅m2/C2. When I worked this, I used the mass of the electron is me=9.11x10-31kg. But that's just out of habit.
- Find the unit vector that points from (x,y)=(-4.5, 7.6) towards (x,y)=(3.4, -6.9). Show your work. Your final answer needs to have the separate x- and y-components shown explicitly as I did in class.
- Find the unit vector that points from (x,y)=(5.2cm, 3.1cm) towards (x,y)=(3.4cm, -6.9cm). Show your work. Your final answer needs to have the separate x- and y-components shown explicitly as I did in class.
- The electric field E at the surface of Earth has an average magnitude of E=120 N/C, and points towards Earth's surface. The average radius of Earth is 6,370km.
a. Find the magnitude of the net charge on Earth.
b. Explain (that's more than one word) whether this charge is positive or negative.