comments on: tips for the sat physics subject test - 加拿大vs摩洛哥欧赔 //www.catharsisit.com/hs/sat/tips-for-the-sat-physics-subject-test/ act, sat, college admissions, life wed, 12 sep 2018 21:35:32 +0000 hourly 1 by: david recine //www.catharsisit.com/hs/sat/tips-for-the-sat-physics-subject-test/#comment-205922 thu, 26 apr 2018 16:49:11 +0000 //www.catharsisit.com/hs/?p=6313#comment-205922 in reply to hcs.

you’re correct that magnitude cannot be negative. to clarify, though, there is one instance when magnitude isn’t positive: magnitude can also, of course, be 0, which is neither negative nor positive. but change in magnitude can be negative, because change measures whether the magnitude becomes greater (positive change) or smaller (negative change). and since the passage is asking for the change in magnitude rather than the magnitude of change, the negative sign only indicates a change downward, and not a truly negative measure of magnitude.

]]> by: hcs //www.catharsisit.com/hs/sat/tips-for-the-sat-physics-subject-test/#comment-205893 mon, 23 apr 2018 19:54:14 +0000 //www.catharsisit.com/hs/?p=6313#comment-205893 in the answers to examples, first question, how
can the *magnitude* of the change in the east-ward
component of the momentum be *negative*? isn’t the
magnitude of a quantity always positive and so the answer
should be (e)? if the question instead asked about the
change in momentum in the easterly direction, then,
of course, the answer would be -4m/s (final momentum minus
the initial momentum = 0 – 4 = -4 m/s)

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