A permanent magnet dc motor is to be started from rest. This motor is driving a load of inertia JL= 0.042 kg-m2, and a load torque of TL= 2 Nm. The motor current must not exceed 15A. First, find the expression of voltage va as functions of time which must be applied to bring this motor to a steady state speed of 300 rad/s as quickly as possible . Then, at time t= 1.2 seconds, what is the voltage va in Volts?

Ametal ring 4.20 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpendicular to the magnetic field. these magnets produce an initial uniform field of 1.12 t between them but are gradually pulled apart, causing this field to remain uniform but decrease steadily at 0.240 t/s . (a) what is the magnitude of the electric field induced in the ring? (b) in which direction (clockwise or counterclockwise) does the current flow as viewed by someone on the south pole of the magnet?

What is the measure of how much matter is in an object and that can be measured using a balance? a. height b. volume c. weight d. mass

You throw a baseball directly upward at time =0 at an initial speed of 14.9 m/s. what is the maximum height the ball reaches above where it leaves your hand? ignore air resistance and take =9.80 m/s2.