Is time real

if everything is relative to gravity

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

The velocity of a car traveling in a straight line increases from 0 meters/second to 30meters/second in 8 seconds. what is the average acceleration of the car?

Robin is swinging back and forth from a trapeze. in which of the following situations is his kinetic energy being transformed into potential energy