What is the terminal velocity of a sheep?
Falling speed is explained in the "Transportation" page on the wiki:
Every tick (1/20 second), non-flying players and mobs have their vertical speed decremented (less upward motion, more downward motion) by 0.08 blocks per tick (1.6 m/s), then multiplied by 0.98. This would produce a terminal velocity of 3.92 blocks per tick, or 78.4 m/s.
Terminal Velocity
As stated above, terminal velocity in Minecraft is 78.4 m/s, but this speed cannot be reached in survival mode:
However, the sky isn't quite high enough for that: Falling from layer 256 to bedrock takes about 5.5 seconds, with impact at 3.5 blocks per tick (70 m/s).
In creative mode, you can fly higher, and could potentially reach terminal velocity falling from "above the sky".
Acceleration
Acceleration is not talked about on the wiki, however see the change in velocity over time in the following graph. The graph was created using the formula:
v(t) = (0.98t - 1) × 3.92
You will notice that acceleration is not constant, and decreases over time.
How Long?
Using the velocity time graph, we can find how long it would take to reach terminal velocity.
10% Terminal Velocity (0.392 blocks/tick) : ≈ 5 ticks (0.4 seconds)
50% Terminal Velocity (1.96 blocks/tick) : ≈ 35 ticks (1.75 seconds)
75% Terminal Velocity (2.94 blocks/tick) : ≈ 69 ticks (3.45 seconds)
99% Terminal Velocity (3.8808 blocks/tick) : ≈ 228 ticks (11.4 seconds)
100% Terminal Velocity (3.92 blocks/tick) : ≈ 672 ticks (33.6 seconds)
Chicken Science!
I couldn't find anything on the falling speed of chickens, so I set my own apparatus to test. It involves a 10 block fall with a pressure plate at the bottom, turning on a redstone lamp. I start the timer at the same time that I press the button, and stop the timer when I see the lamp turn on:
I timed the fall of 3 different chickens to ensure accurate results:
Test 1: 5.0 seconds
Test 2: 4.9 seconds
Test 3: 5.1 seconds
This averages out at 5 seconds for a chicken to fall 10 blocks. Using the formula for speed we can calculate the speed of a falling chicken:
speed = distance / time
speed = 10 / 5
speed = 2 m/s
∴ The falling speed of a chicken is 2 m/s.
Higher?
As per the OP's request, I did the test again at a greater height, 50 blocks to be exact:
I timed the test the same as the others, and received another result:
Higher Test 1: 25.0 seconds
The first test I did came back with 25 seconds flat, I didn't feel a need to repeat any more tests:
speed = distance / time
speed = 50 / 25
speed = 2 m/s
Note: I was using unladen European chickens. I also noticed that chickens reach their maximum velocity as soon as they started falling.
No chicken were harmed in the making of this answer:
