Susan C. answered • 06/16/24
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Physics Tutor - Conceptual, College Prep, Honors and AP Physics 1
Hi! This is a simple torque problem. The only small "trick" is that they gave the radius in cm. You need to make sure you are working in SI Units. Also be sure to be in degrees!
So for this problem:
Given:
Force Applied (F) = 50 N
Angle (Θ) = 15°
Radius (r) = 30 cm → 30/100 → 0.3 m
Equation:
Torque = radius × Force × sin Θ or τ = rFsinΘ
Math:
τ = 0.3 × 50 × sin 15
Solve:
τ = 3.88 N·m
Susan C.
tutor
No problem! I hope it helped :)
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06/16/24
Ariel B.
tutor
Hi Annet,
I guess It would be a good habit to assume (even if not explicitly required in the problem) that significant figures ("sig.figs.") ARE indeed significant. One must then round the final results to the lowest number of significant figues among the input data. Therefore the result 3.88 N.m must be rounded to 3.9 N.m (but not, e.g. to 3.90N.m) to be consistent with the input data 15;30;50 carrying only 2 sig.figs. Also, the radius of 30cm should be converted to 0.30m rather than 0.3m (as the latter has only 1 sig.fig.)
Hope this note would help you not only in this one but in solving ANY problems involving measured data as they must always be presented not as just numbers (with units of course) but must be supplanted with how accurate those numbers are. Treating sig.figs. lightly might not only cause a potential of grades lowering on a homework or class test but if happening in e.g. engineering could potentially lead to a misjudgement of safety of some critical element in equipment like space craft where the very life of the pilots inside would depend on that accuracy, on that number of sig.figs.
Best,
Dr.Boroda
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06/19/24
Annet N.
Thank you!!06/16/24