The MICROSCOPE mission tested the weak equivalence principle with free-falling objects in a satellite. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it ...

When an object is falling, the two main forces acting on it are weight close weightA force that acts on mass, pulling it down, due to gravity. Weight is a force and forces are measured in newtons (N).

Our motion perception is remarkably well tuned to detect small changes in speed and direction. For example, soccer goalkeepers need to precisely judge the speed, direction, and curvature of an ...