Type o blood is known as the universal donor why is this so?

Explain earth's motion, using the terms "precession" and "rotation" in your answer.

Alead ball is dropped into a lake from a diving board 5m above the water . it hits the water with a certain velocity and then sink with constant velocity in bottom . it reaches the bottom 5 second after it is dropped if g= 10m/s2 . find depth of the lake and average velocity of the ball ?

Wavelength of 125 meters is moving at a speed of 10 m/s. what is it's frequency?