A traditional problem has a particle sliding down an incline on a movable wedge. An airtrack glider was modified to serve as such a system; the measured results for the acceleration were compared to predictions based on a model (a) neglecting friction and (b) including friction. Some experimental considerations are discussed. The system exhibits interesting features, including an angle of maximum acceleration that has a value dependent on the coefficient of friction on the incline.

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The paper describes a theoretical and experimental investigation of the stress distribution across the walls of thick cylinders of mild steel when the internal pressure is such that the elastic limit of the material is exceeded and a certain amount of overstrain occurs. The main conclusions are:— (1) That in the cylinders in which it was possible to produce overstrain over the whole wall thickness the observed pressure is in close agreement with that calculated on the assumption of constant shear stress equal to the shear stress observed during plastic yield in tension. (2) That in partially overstrained cylinders the maximum shear stress in the elastic region varies as overstrain proceeds. (3) That at the internal surface the effect of overstrain is to reduce the circumferential tensile stress, and to set up an axial compressive stress. With sufficient wall thickness all three principal stresses at the internal surface become compressive for pressures which still permit of the external portions remaining elastic.

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