Which of these objects could be falling with constant acceleration?

1 and 2

Explanation:

If an object has constant acceleration, it's displacement at time t is:

Δx = v₀ t + ½ at²

For object 1:

0.44 = (0) (0.3) + ½ a (0.3)²

a = 9.78

3.14 = (0) (0.8) + ½ a (0.8)²

a = 9.81

So object 1's acceleration is approximately constant.

For object 2:

0.06 = (0) (0.3) + ½ a (0.3)²

a = 1.33

3.09 = (0) (2.1) + ½ a (2.1)²

a = 1.40

So object 2's acceleration is approximately constant.

For object 3:

0.44 = (0) (0.3) + ½ a (0.3)²

a = 9.78

3.09 = (0) (2.1) + ½ a (2.1)²

a = 1.40

So object 3's acceleration is not constant.

3. dark matter

empty space could also be a simple vacuum