# [Physics] Lab observation correct? As distance decreases, velocity increases, stderr decreases

data analysisexperimental-physicshomework-and-exerciseskinematics

The experiment goes like this:

Allow a moving cart to move from the top of an incline plane ($x_0$) downwards. The time taken will be recorded by the picket fence (those things you see wired up). Distance ($D$) is reduced by 10cm each time. And a set of recordings are recored as follows:

Does the recording seem logical?

• As $D$ decreases, $v$ increases? Why, I thought $v$ should reduce as there will be less effect from gravity?
• As $D$ decreases the standard error decreases. It kind of makes sense as the time interval will be smaller and thus less chance of error. However, I would think if the $D$ is too small, the cart may not have stabalized or something? But that doesn't sound scientific.
• Is my calculation of standard error right? Or should it be standard deviation here? When do I use which?

It seems that the cart is always released at the top. It is the first picket fence which is moved. Thus smaller $D$ means you confine the measuring too the high speed regions of the track. At the last measuring you effectively measure the final velocity of the cart at the bottom.