How long will it take for sound impulse to travel to copper rod 25 kilometers long?

0.071 seconds
7.1 seconds
140 seconds
0.14 seconds

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.

radial fractures in a piece of glass look most like which of the following?

a. spokes of a wheel

b. a circle

c. a zig zag

d. none of the above

the correct answer is a. spokes of a wheel

hope this (: