PLS HELP! What is a spring constant?

Explain what it means to view something from a frame of reference. provide an example that illustrates your explanation. (4 points)

Aball is thrown horizontally from a cliff at 8m/s .in what direction is the ball moving 2s later?

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