Question

If an hour hand is .01667 rev/s, a minute hand is 2.78e-4 rev/s, what is the second hand rotation speed? I've tried everything and can't get a correct answer.
Thank you

Answer 1

Correction. The Hour Hand is 2.31e-05 rev/s; the Minute Hand is 2.78e-4 rev/s. I've checked with 3 tutors and none of them have gotten an answer that works for the Second Hand rotational speed in rev/s. Thank you

Answer 2

the hour hand makes one revolution each 12 hours, the minutehand makes on rev each 60 min.

speed minute hand=speedhourhand*12
= 2.31E-5*12= 2.78E-4 rev /sec
The second hand makes one rev per min. or

speed second hand=speedminutehand*80
= 2.78E-4 rev/sec* 60= = 0.01668 rev/sec

check: the second hand should rotate one rev in sixtysecond
60*.01668=1 rev

Answer 3

answer key marks that as incorrect.
thanks though