Actually, I am gonna do a centripetal force apparatus lab tmr morning. Here I get some pre-lab questions. In this lab, we are gonna use economy force sensor (as I know there are 2 types, but it doesn't matter). There is one question related to this sensor... It says "The 'Tare' button on the economy force sensor is to set the force to be zero. How to verify the result? Hint: Observe the curve." First question, what result? That the force is really zero? Is the voltage of the electric motor 0V indicating that the force is 0N? Second question, what curve? I don't get the relation of it with voltage. Or is it not related to the voltage? Besides, in the experiment of Centripetal force vs Mass, there is a question asking whether the velocity is a constant or not. It seems an easy question and I should know... But somehow I forget it. Is the velocity increasing with the radius and thus keeping v2/r a constant? Or both v and r are constants so that v2/r is already a constant? Thank you.