If the pendulum of a clock swings through an angle of 2.8 radians and the length of the arc that its tip travels is 40, the length of the pendulum is what?

Question

A)12.54
B) 13.58
C) 14.29
D) 52
E) 112

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Answer 1 · 2018-03-17T22:27:44

#r=100/7 larr" Exact answer"#

#r~~14.29 " to 2 decimal places "larr" Approximate answer"#

Set the radius of the arc as #r#

A radian measure is such that the length of the loci (path) of the tip of the radius is exactly the same length of the radius.

Tony B

The angular measure is #2.8# radians

So we have #2.8xxr=40#

#=>r=40/2.8 = 14.2857...# but this is not a precise value.

Multiply by 1 and you do not change the value,. However 1 comes in many forms. Note that #10/10=1#

#r=[40/2.8xx10/10]=400/28 = 200/14=100/7#
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