The atomic number of sodium (Na) is 11. The element phosphorous (P) is the fourth element to the right of sodium in the periodic table. The atomic number of phosphorus is ---
. It has zero charge because it has
electrons.

As a car drives with its tires rolling freely without any slippage, the type of friction acting between the tires and the road is 100) a) static friction. b) kinetic friction. c) a combination of static and kinetic friction. d) neither static nor kinetic friction, but some other type of friction. e) it is impossible to tell what type of friction acts in this situation.

When the force acting on an object points at least partially in the direction of the motion the work done is considered to be negative

Two resistors r1 and r2 may be connected either in series or parallel across an ideal battery with emf ε. we desire the rate of energy dissipation of the parallel combination to be 8.75 times that of the series combination. if r1 = 105 ω, what are the (a) smaller and (b) larger of the two values of r2 that result in that dissipation rate?