In a quarter of an hour it will travel 1/4 x 90 = 22.5Km
Because of the location of Mg on the periodic table.
Answer:
Backwash effect
Explanation:
Your friend moved along the shore due to ; The swash effect and the Backwash effect
Swash effect is caused by the upsurge of water up along the slopping front of the beach and this same upsurge in water moves back into the beach in what is known as the backwash effect hence the movement of your friend form where they were in the surf zone to another position still within the surface zone is caused by the BACKWASH EFFECT