Please help to find something for my science project part...?

Question

What I need is something like a bicycle's brake lever on the handlebar. But instead of jumping back when you release it, it will stay at any position in between as I set with my hand even if it is under (spring ) pressure. Is there anything like this that exists?

Answer 1

Yes there is, and its also found on bicycles:
The lever for changing gears. It has a friction disc inside to overcome the gear set's spring load, but you can still move it with your finger. The friction can be adjusted by a screw in the rotation axis.