A bullet with a mass of 0.3 kg is fired out of a gun with a mass of 4 kg at 600 m/s. What is the recoil velocity on the gun? 200 m/s
45 m/s
2400 m/s
90 m/s

According to the Conservation of Momentum,

Momentum of the gun = momentum of the bullet

M(gun)×V(gun)=m(bullet)×v(bullet)

4kg × V = 0.3kg × 600m/s²

V = (0.3 × 600)/4 = 45 m/s

The recoil velocity on the gun is 45 m/s

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

i believe the answer would be:

d. violin, clarinet, french horn, and tuba