Two similar metal spheres are side by side. One has a charge of -7 x 10^-6 C and the
other is neutral. After contact and separation,
what is the charge on the sphere that was
initially neutral?
+7 X 10^-6 C
Ос
-7 X 10^-6 C
-3.5 X 10^-6 C
+3.5 X 10^-6 C

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.

Large electric fields in cell membranes cause ions to move through the cell wall. the field strength in a typical membrane is 1.0 x 10 7 n/c. what is the magnitude of the force on a calcium ion with charge +e? what is its acceleration? is it possible for a particle with the same charge as as calcium to have a different acceleration if placed at this location? what would change the acceleration: mass of the particle? diameter of the particle?

Which system of units is used by only a small number of countries in the world, including the u. s.