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?

Abeam of electrons with of wavelength of 7.5 x 10-6 m is incident on a pair of narrow rectangular slits separated by 0.75 mm. the resulting interference pattern is projected onto a screen 10.0 m from the slits. what is the separation of the interference maxima in the resulting interference pattern?

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.

Avoltaic cell converts chemical energy to