I will mark as brainlest if you can answer all of the questions

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

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

During a car accident, a 125kg driver is moving at 31m/s and in 1.5s is brought to rest by an inflating air bag. what is the magnitude of the change in momentum to the driver