The uniform thin rod with mass m and length I stands upright with a hinge below. At the beginning, the rod is stationary. Because it is in unstable balance, it falls down. The angular acceleration and angular velocity when it forms a 60 ° angle with the lead line are calculated

The uniform thin rod with mass m and length I stands upright with a hinge below. At the beginning, the rod is stationary. Because it is in unstable balance, it falls down. The angular acceleration and angular velocity when it forms a 60 ° angle with the lead line are calculated

It is known that the sinusoidal AC voltage U1 = 311sin (314T) V, U2 = 100sin (314t-45 °) v
1. What is the reading of u1u2 measured by AC voltmeter?
2. Compare the phase relationship of u1u2?

U1 = 311 / radical 2 = 219.94v
U2 = 100 / radical 2 = 70.72v
U2 is 45 degrees ahead of U1

It is known that sinusoidal voltage U = 311sin 314T, when T -- 0.01 s, the instantaneous value of voltage is ()

The general formula is: u = um sin ω T, ω is angular frequency, unit is radian, ω = 2 π, f = 314, f = 50 Hz, period T = 1 / F = 20 ms, um is the maximum, effective value u = um / √ 2 = 311 / √ 2 = 220 v