Tension is maintained in a string as in Figure P13.57. The observed wave speed is 24 m/s when the suspended mass is 3.0 kg. (a) What is the mass per unit length of the string? (b) What is the wave speed when the suspended mass is 2.0 kg? FIGURE P13.57 3.0 kg
Goals • To study electric charge and charge conservation • To see how objects become charged • To calculate the electric force between objects using Coulomb’s law • To learn the distinction between electric force and electric field • To calculate the electric field due to many charges • To visualize and interpret electric fields Introduction • Water makes life possible as a solvent for biological molecules. What electrical properties allow it to do this • We now begin our study of electromagnetism, one of the four fundamental forces. • We start with electric charge and look at electric fields. Electric charge • Two positive or two negative charges repel each other. • A positive charge and a negative charge attract each other.
