For which optical devices does d sometimes have a positive value?

Rosa records the distance that a toy car rolls and the time it takes to cover the distance. what scientific practice is this? collecting data asking a question providing explanations communicating results

What is a neurotransmitter involved in mood reward, addiction, and motor behaviors?

The rocket is fired vertically and tracked by the radar station shown. when θ reaches 66°, other corresponding measurements give the values r = 32700 ft, r¨ = 85 ft/sec2, and θ˙ = 0.019 rad/sec. calculate the magnitudes of the velocity and acceleration of the rocket at this position.