On a trip a motorist travels at 80 km/h for the first 200 km, and 60 km/h for the remainder of the trip. if the trip is 300 km in total, calculate the average speed for the whole trip.

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.

According to social exchange theory, altruistic behaviors benefit the individual who performs them. t/f

Explain why electric current cannot exist if a current doesn't have a voltage source.