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

The total displacement for the bike ride of Johnny is ' 0 km'. This total displacement is determined my calculating the difference between the initial point (starting point) and the final point (finishing point). Since, Johnny started from his home and came back to his home, the total distance between these points is 0. Hence, the displacement is zero.

His friend's house can be used as a reference point to determine Johnny's motion during his bike ride. As Johnny will keep moving on his bike, the distance from his friend's house will keep on decreasing. And he will come back to his house, the distance between his friend's house and his bike will keep on increasing.

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave