1.5. Further reading[[Student version, December 8, 2002]] 25
force and potential energy of a spring,f=kx,E=^12 kx^2.
potential energy in Earth’s gravity =(mass)·g·(height).
potential energy of a charged object in an electrostatic potential field =qV.
electric field,E=−dV/dx.
force on a charged body,f=qE.
electric potential created by a single point chargeqin an infinite, uniform, insulating medium,
V(r)=q/(4πε|r|), whereεis the permittivity of the medium.
The electrostatic self-energy of a charged sphere of radiusaisq^2 /(8πεa).
Ohm’s law,V=IR;powerloss from a resistor,I^2 R.
electric potential drop across a capacitor,V=q/C.
electrical potential energy stored in a capacitorE=^12 q^2 /C.
capacitance of a parallel-plate capacitor of areaAand thicknessD,C=Aε/D.
2.Mechanical equivalent of heat: One joule of mechanical energy, when completely converted
to heat, can raise the temperature of 1gof water by about 0. 24 ◦C(Equation 1.2).
3.Ideal gas: The pressure, volume, number of molecules, and temperature of a confined ideal
gas are related bypV =NkBT (Equation 1.11). At room temperatureTr,the quantity
kBTr≈ 4. 1 pN nm(Equation 1.12).Further reading
Semipopular:
Heat: (von Baeyer, 1999; Segr`e, 2002)
The Second Law: (Atkins, 1994)
Franklin’s oil experiment: (Tanford, 1989)
Intermediate:
General physics with biological applications: (Benedek & Villars, 2000c; Benedek & Villars, 2000a;
Benedek & Villars, 2000b; Hobbie, 1997)
Technical:
Biophysical Society’s On-Line Textbook:http://www.biophysics.org/btol/