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小 發表於 2016-2-20 02:25 PM (第 2960 天)
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some concept questions
1. vector question
if R is vector , then R=Rx+Ry
if R is scalar, then R^2= Rx ^2 + Ry ^2
however, when I need to find the magnitude of force, why use R^2= Rx ^2 + Ry ^2? ( as I think force is a vector)
if the queston ask me to find the final velocity of an object, should I use R=Rx+Ry or R^2= Rx ^2 + Ry ^2?
2.Does the airplane flying on sky have normal reaction force?
3. in circular motion, is tangential acceleration equals to instantaneous velocity of an object?