What's the volume of the tennis ball

Why do scientists believe that light is made of streams of particles? scientists believe that light is made of streams of particles because only the presence of photons can explain phenomena observed during experiments on the photoelectric effect. these observations include only some frequencies of light causing the ejection of electrons, no time gap existing between light striking a metal and electrons being ejected, and intensity having no effect on the kinetic energy of the ejected electrons.

The free body diagram shows a box being pulled to the left up a 25-degree incline. the magnitude of the normal force is

Debbie places two shopping carts in a cart corral she pushes the first cart which then pushes a second cart what force is being exerted