At what minimum speed must a roller coaster be traveling so that passen- gers upside down at the top of the circle (Fig. 5–48) do not fall out? Assume a radius of curvature of 8.6 m.

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?