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    A question on Dimensional analysis

    This is actually an example from Physics for Scientists and Engineers by Serway. I am confused about the way they solved it. Homework Statement Suppose we are told that acceleration a of a particle moving with uniform speed v in a circle of radius r is proportional to some power of r, say...
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    Is Time a vector quantity?

    Ok I am not serious here. I was just wondering - as for us, time always moves forward; doesn't that mean time have a direction? So why not call it a vector? :-)
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    Centripetal vs Radial acceleration

    I am reading introductory physics from Serway. Where they say if a_r is radial acceleration and a_c is centripetal acceleration then a_c = v^2/r and a_r = -a_c = - v^2/r But aren't the radial and centripetal acceleration same (correct me if I am wrong)? Why is there a minus sign? The...
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    A basic question about free fall (concerning Galileo and Aristotle)

    This question is from Resnick, Halliday, Krane; Physics 5th edition. This is not actually a homework problem rather a question and so I hope it's not inappropriate to post it here. If m is a light stone and M is a heavy one, according to Aristotle M should fall fall faster than m. Galileo...