Comments on a news item on rail traffic that is meant to promote conservation of energy. (GA)

Consideration of the force of gravity in some simple accelerated systems. Ambiguity about the use of up'' and down'' arises in coordinate systems not at rest with respect to the surface of the earth. (DF)

Scientists often use the "slingshot effect" (also called the "gravity assist") of the gravitational field of a planet to increase or decrease the velocity of a spacecraft. Examples of this effect, puzzling aspects, a qualitative explanation, details of necessary calculations, a thermodynamic analogy, and other topics are discussed. (JN)

Defines frame of reference for the analysis of motion in a moving car, discussing the interaction of the car body, the seat springs, and the passenger when the car goes over a bump. Provides a related, but more advanced, problem with the motion of cars involving angular acceleration. (JM)

Four questions related to rain concerning aerodynamic drag force, pressure from the impact of raindrops, impact of wind on the pressure, and stopping force extended on the car by the water are proposed. (YP)

Discusses the velocity of an orbiting satellite. Knowledge of the kinematics of falling objects is the only prerequisite for understanding the concepts considered. (DH)

Discusses free-fall acceleration in accelerated frames of reference of moving cars. Specifically, evidence presented by oil leaks on pavement is used as an example of exploring this phenomenon. (CS)

Attempts to determine, using estimations and current power-law relationships, whether a newspaper report concerning the statement that a single 40,000-kg truck does as much damage to the highway as 9,600 cars is true. Provides a mathematical and graphical possible solution. (MVL)