A grinding wheel, initially at rest, is rotated with constant angular acceleration of 7.1 rad/s 2 for 12.2 s. The wheel is then brought to rest with uniform deceleration in 6.46 rev. Find the angular acceleration required to bring the wheel to rest. Note that an increase in angular velocity is consistent with a positive angular acceleration. Answer in units of rad/s 2 .

An electromagnetic wave with frequency 65.0 hz travels in aninsulating magnetic material that has dielectric constant 3.64 andrelative permeability 5.18 at this frequency. the electric fieldhas amplitude 7.20 \times 10^{ - 3} {\rm v}/{\rm m}. a. what is the speed of propagation of the wave? b.what is the wavelength of the wave? c.what is the amplitude of the magnetic field? d.what is the intensity of the wave?