How does friction affect the results of the ticker tape experiment?

[shinks]

I did the ticker tape experiment.

Made a ramp, attached ticker tape to the end of a cart, thread the tape through the ticker timer, let the cart roll down the ramp ^.^''

My question; let's say my ramp had an imperfection, like a bumb or groove. How would that show up on my ticker tape? What would it look like?

And also the experiment was designed to compensate for the effect of friction. Can you explain how this was done?

 

[Dick]

A bump or groove would show up as a deviation from uniform acceleration. Don't you compensate for friction in the usual way by using an air track? Or is it more exotic?

 

[andrevdh]

When the cart accelerates down the track the distances between ticks will grow constantly. When it encounters an obstacle in the track the cart will be slowed down momentarily. This will be made visible on the tape as a shorter distance between the ticks as the cart was slowed down momentarily.

Friction introduces a force that will retard the motion of the system. To eliminate its effects one needs to add a force to the system that cancels it out. In the case of the ramp this might be achieved by offsetting the angular measurement of the ramp or introducing a mass that is not used in the calculations.