Falling slowly on wood

Summary:
My sister was in creative flat, and had a tree house. She stacked some logs, and fell down from it, but she fell slowly.
What I expexted to happen was:
To fall at normal speed
What happened was:
She fell at the speed of going down from a ladder
Steps to reproduce:
1.Stack a tall stack of jungle wood on the ground
2.Fall from the top of it. Be sure not to fly!
3.While falling, aprroach the wood and press and hold the back key
4.See how you fall slowly, like you were on a ladder