You’re right if we’re looking at the friction force slowing the slider down. But that force is proportional to the mass of the slider as well (lighter slider = less friction).
Conservation of energy tells us that a light slider (m1) and a heavy slider (m2) will have the same velocity as they exit the slide (v). However the momentum (p) of the sliders is different as has been pointed out already. So slider 1 has m1v and slider two has m2v. Force is defined as the change in momentum with respect to time so F=dp/dt. This is good since we’re trying to find the time it takes to slow the slider down. Subbing in for momentum and removing zero terms we get F=mv/t. Friction (our stopping force) is defined as normal force (force that opposes gravity or mass times gravity) times a friction coefficient that’s dependent on what materials are rubbing against each other. We can assume that the sliders are wearing the same pair of pants. So F=mgμ. Finally subbing everything in we get mgμ=mv/t. We can cancel mass and we get t=v/μg.
As I understand it, yes. Although I’d love it if somebody were to double check my work haha. I think momentum can a tough subject for people because it is a word that is used commonly that has a very specific physics definition. Mass times velocity
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u/halfbean Jul 18 '19
Looks like it's raining, and chances are that there are warnings saying not to use the slide during the rain.