Provides an analysis of the forces causing the erratic motion of a knuckleball. Reveals the manner the ball should be thrown to provide maximum deflection. (Author/CP)

The circular motion observed when water drains into a smooth opening is analyzed. This action, as well as cycloidal atmospheric motion, is explained as the result of rotation of the coordinate system. (CP)

Reports on a small-scale investigation of student understanding of moments of forces to provide some indication as to the nature of intuitive ideas in this area. Results of the investigation suggest three stumbling blocks in the conceptual understanding of moment of forces. (Author/ASK)

Provides directions for a three person rotating reference system. A series of experiments used with the apparatus is also described. (CP)

Describes construction of an exhibit which uses the acceleration of an elevator to distinguish mass and weight. (CP)

Describes a rocket propulsion demonstration utilizing a child's wagon and a carbon dioxide fire extinguisher. (CP)

Explains a method of exploiting recent interest in automobile safety to demonstrate, qualitatively, concepts of momentum and energy. (GS)

Describes experiments simulating the mechanics of the human elbow and back. (SL)

Presents results of analyses of flat and conical depressed target surfaces used in a bouncing ball experiment. (SL)

In response to conventional rocket demands on fuel supplies, electromagnetic launches were developed to give payloads high velocity using a stationary energy source. Several orbital mechanics problems are solved including a simple problem (radial launch with no rotation) and a complex problem involving air resistance and gravity. (DH)

Describes a student project in which paper planes were designed and flown to investigate the effect of the wing area to mass ratio on aircraft performance. (GS)

Describes a laboratory experiment that demonstrates the simultaneous conservation of angular and linear momentum. (Author/CP)

Derives the precessional period of a Foucault pendulum without using small oscillation amplitudes. Shows that if the path of the pendulum passes through the origin, the periods for differing amplitudes are essentially the same. (GA)