Fermi scattering and transit time damping have been suggested as two possible mechanisms for accelerating low-energy protons (~1 Mev) in corotating particle streams. In this paper the requirements and properties of each of these mechanisms are illustrated by means of numerical solutions to the equations which govern particle behavior in such streams. It is found that the conditions which are required for Fermi scattering to be the dominant acceleration mechanism are more extreme than those required for the transit time damping. Acceleration by Fermi scattering requires a scattering mean free path more than an order of magnitude smaller than the nominal value for low-energy particles of 0.1 AU. Transit time of only the observed low level of magnitude fluctuations in the interplanetary magnetic field appears to yield the required acceleration rate. Measurements of the direction of the anisotropy in the particle streams could of help in deciding which of these mechanisms (if either) is operative. In the case of Fermi scattering the anisotropy must be in the heliocentric radial direction, whereas for transit time damping a significant azimuthal anisotropy could be present.