An ion has unequal numbers of which two particles?

Which sound characteristic is not affected by the relative motion of an object

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:

Is there a point between a 10 nc charge and a 20 nc charge at which the electric field is zero?