A "Jan-van-gent" is the biggest sea-bird on the North-sea. The average mass of this bird is 2.8 kg. When he dives to catch fish his velocity exceeds that of 100km/h. a) If we know that he dives from a height of 30 meters, with a starting velocity of 0 m/s, what is its velocity when he hits the water? b) With his wings, he gets a velocity of 25m/s in 0.82 s. From t= 0,82 s only gravitation does work. The bird is at that moment 28 m above the water Calculate the velocity he achieves as he hits the water