What is the meaning of the phrase "grand unified theories" when applied to particle physics and cosmology?

1. in terms of fuel economy rank the following hybrid and electric vehicles, and justify application specific to each hybrid technology stop/start | mild hybrid | full hybrid | plug-in hybrid | full electric a. rank based on fuel economy b. justify your application specific for each technology

Choose the most likely outcome of this scenario: jen decided to go bike riding without a helmet. while no one is around during her ride, she is thrown from her bike when her wheel goes into a pothole. she is not injured, but she is terrified to get back on her bike. what happens next? a. her physical health is affected even though she wasn't hurt. b. her mental and emotional health are affected because she is afraid to get back on her bike. c. her social health is affected because she is worried her friends saw the fall. d. her overall health is not affected at all by her fall.

Positrons are spontaneously emitted from the nuclei of