What is an atom that has gained electrons in order to become stable?

Awave is produced in a rope. the wave has a speed of 33 m/s and a frequency of 22 hz.

Amachinist turns the power on to a grinding wheel, at rest, at time t = 0 s. the wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 96 rad/s. the wheel is run at that angular velocity for 40 s and then power is shut off. the wheel slows down uniformly at 1.5 rad/s2 until the wheel stops. in this situation, the time interval of deceleration is closest to:

The voltage applied across a given parallel-plate capacitor is doubled. how is the energy stored in the capacitor affected?