Discusses Newton's apparent oversight of the role of energy considerations in collisions between two spherical bodies related to the third corollary of his "Laws of Motion." Investigates several theories that provide solutions to the mysterious oversight. (LZ)

Investigates the concept of animacy of 9- and 12-month-old infants by exposing them to autonomous motion with animate and inanimate objects in a series of three experiments. Three experiments were carried out. Results indicated that infants discriminate animate from inanimate objects on the basis of motion cues by the age of nine months. (MOK)

In six experiments, infants were habituated to word-object pairings and then presented with a familiar word and object in a previously seen and a new pairing. Found that 14-month olds formed word-object associations under these conditions when the objects were moving; 8- to 12-month olds did not form associations but appeared to process the word…

A review of applications of motion study in developmental disabilities identifies two eras of research focus in the 1990s: (1) studies establishing the effectiveness and efficiency of tasks designed with motion study principles and (2) studies examining the interaction between motion study-based task designs and other variables such as choice,…

Argues that it is possible to get a smooth ride on noncircular wheels on a smooth road if the load is supported using the wheels as rollers. Illustrates that the key to getting a smooth ride is for the rollers to measure the same height from top to bottom, regardless of how they are rotated. (CCM)

To determine the contributions of the motions of the body segments to the vertical ground reaction force ([F.sub.z]), the joint torques produced by the leg muscles, and the time course of vertical velocity generation during a vertical jump, 15 men were videotaped performing countermovement vertical jumps from a force plate with and without an arm…

The equation of motion for a mass that moves under the influence of a central, inverse-square force is formulated and solved as a problem in complex variables. To find the solution, the constancy of angular momentum is first established using complex variables. Next, the complex position coordinate and complex velocity of the particle are assumed…

Young students are familiar with the observable effects of force and motion but may not have considered the many varieties demonstrated in simple ways every day on the playground. A force is simply a push or a pull. A force can make an object move, move more quickly, change direction, slow down, or stop. Forces cannot be seen but their effect can…

This article briefly describes an activity for students to illustrate the relationship between orbital period and orbital motion. To do this, students should calculate the degrees per day that planets travel and then graph them as a function of orbital time. A brief list of resources is also included.

How do we understand time and other entities we can neither touch nor see? One possibility is that we tap into our concrete, experiential knowledge, including our understanding of physical space and motion, to make sense of abstract domains such as time. To examine how pervasive an aspect of cognition this is, we investigated whether thought about…

A flashed stimulus is perceived as spatially lagging behind a moving stimulus when they are spatially aligned. When several elements are perceptually grouped into a unitary moving object, a flash presented at the leading edge of the moving stimulus suffers a larger spatial lag than a flash presented at the trailing edge (K. Watanabe. R. Nijhawan.…

In 3 experiments, the authors investigated changes in hand orientation during a 3-D reaching task that imposed specific position and orientation requirements on the hand's initial and final postures. Instantaneous hand orientation was described using 3-element rotation vectors representing current orientation as a rotation from a fixed reference…

Human observers demonstrate impressive visual sensitivity to human movement. What defines this sensitivity? If motor experience influences the visual analysis of action, then observers should be most sensitive to their own movements. If view-dependent visual experience determines visual sensitivity to human movement, then observers should be most…

The emerging ability to represent an oscillating moving object over occlusions was studied in 7-21-week-old infants. The object moved at 0.25 Hz and was either occluded at the center of the trajectory (for 0.3 s) or at one turning point (for 0.7 s). Each trial lasted for 20 s. Both eye and head movements were measured. By using two kinds of…

In order to understand ongoing activity, observers segment it into meaningful temporal parts. Segmentation can be based on bottom-up processing of distinctive sensory characteristics, such as movement features. Segmentation may also be affected by top-down effects of knowledge structures, including information about actors' intentions. Three…