According to scientific evidence, earth’s earliest atmosphere lacked oxygen. over time, oxygen was added to the atmosphere.
which statements explain how this change occurred and how it affected life on earth?
choose all answers that are correct.
a.
oxygen is needed to carry out photosynthesis. when cyanobacteria evolved, they began to carry out photosynthesis.
b.
adding oxygen to earth's atmosphere allowed for the development of prokaryotic organisms, which need oxygen to carry out many of their life processes.
c.
adding oxygen to earth's atmosphere allowed for the development of eukaryotic organisms, which need oxygen to carry out many of their life processes.
d.
oxygen is a product of photosynthesis. when cyanobacteria evolved, they began to carry out photosynthesis.

A & D, photosynthesis came first before oxygen, giving legitamicy to both these events

    m₁v₁ + m₂v₂ = (m₁ + m₂)vmomentum is conserved.the left-hand side of the equation represents the momentum in the system before the collision.the right-hand side represents the momentum in the system after the collisionm₁ and v₁ represents the mass and the velocity of the physics blockm₂ and v₂ represents the mass and velocity of the ball of puttyv represents the final velocity of the combined mass.the question states the two masses stick together. they combined mass has its own velocity with the body mass the sum of the two objects' massestheir combined momentum is (m₁ + m₂)vto find the magitude of (m₁ + m₂)v, we need to add the vectors on the left-hand side of the equation: m₁v₁ + m₂v₂.note the diagram. i have positioned the vectors in accordance with their directions.the magnitude of the resultant can be calculated using the pythagorean theorem since this is a right triangle situation (north and west are perpendicular)|(m₁ + m₂)v| =  √[ (m₁v₁)² + (m₂v₂)² ]|(m₁ + m₂)v| =  √[ (1.5kg·8.0m/s)² + (0.40kg·20m/s)² ]|(m₁ + m₂)v| =  14.4 kg m/sfor two significant figures (assuming that 20m/s is two), this rounds to 14 kg m/s

The fuzzy edges of shadows are a result of  diffraction