I am confused as to when I should be able to tell "by observing" whether the forces of normal, kinetic friction, and tension need to be added or subtracted from the net force for both sideways and vertical directions. Ropes pulling at degrees, pulleys moving up and down, cars traveling uphill, how do I know when to subtract or add these forces from [tex]\Sigma[/tex] F (x or y) ?(adsbygoogle = window.adsbygoogle || []).push({});

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# About simple forces

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