What country sent the first man to space

In which situations is the principle of cross-cutting relationship useful in determining relative age?

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point

Which type of stimulus do mechanoreceptors detect? sound pain heat light