In physics 28.97 + 45.876 adds up to what?

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body

Adolphin emits ultrasound at 100khz and uses the timing of reflections to determine the position of objects in the water. part a what is the wavelength of this ultrasound? assume that temperature of water is 20 degrees c. answer in cm

Diego kicks a soccer ball from the end line. his fellow students time and mark the soccer ball as it moves down the field. the graph represents the ball's progress. based on the graph, during what time is the velocity constant and positive?