# Two questions on acceleration and an experiment

1. Jul 18, 2012

### skywoo

Hi.

First post here and not a native english speaker, so be kind :-)

1) I have never really understood what it means when we say that the gravitation accelerations is 9,82 m/s2

What is the practical use. Could anyone tell me with a simple example. I think the confusing part is the s2.

2) I have seen an experiment relating to one of newtons laws which consitet of a wagon moving down a hill. At some point a spring on the wagon was released which made the ball flying and landing in the wagon (which had already moved). Does this experiment have a name?

Thanks in advance. I hope you can help :-)

2. Jul 18, 2012

### Mark M

It means that, for every second you are in free-fall, your velocity towards the earth increases by 9.8 meters per second. If I jump from a plane with a velocity of 0 meters per second, and it takes me 200 seconds to reach the ground, my velocity will be about 2000 meters per second when I reach the ground.

It doesn't have a name as far as I know of. It's demonstrating that the velocity in the X direction is independent of that in the Y direction.

3. Jul 19, 2012

### skywoo

Thank you! Helped a lot.