A coin of mass m is placed on top of a horizontal turntable a distance R from the axis of rotation. Gravity is acting vertically downward with magnitude mg and the normal force on the coin from the turntable is acting vertically upward. The coefficient of static friction between the coin and the turntable is µ. If at time t = 0 the turntable is at rest and accelerates with a constant angular acceleration α < µg/R, at what time T will the coin begin to slide on the turntable?

Astudent is performing an experiment comparing sound and light waves. the student gathers the following data. what conclusion does the student most likely make based on this data? light waves always travel the same speed; however, the speed of sound is determined by the medium that it travels through. all sound waves always have the same energy, so the temperature of the medium does not affect wave speed. light needs to vibrate particles, so it travels fastest in tightly packed solids, while sound does not need a medium, so it travels fastest in a gas. tightly packed particles in solids slow down the light waves; however, sound waves make particles bounce into each other, so they travel faster in solids.

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.

Ryan is examining the energy of the particles in a bar of gold. what is ryan most likely studying?