How many electron shells does an atom of oxygen have? (a.) 1 (b.) 2 (c.) 3 (d.) 4

The image shows a pendulum in simple harmonic motion the pendulum starts at a and swing to e

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?

What is friction? how does it affect the motion of an object?