Solution.
"m_1=60kg;"
"m_2=100kg;"
"l=4.50m;"
"\\upsilon=\\dfrac{2\\pi R}{T};"
The period of rotation of the needle:
"T=12 hr=43200 s;"
Needle rotation speed:
"v=\\dfrac{2\\sdot3.14\\sdot4.50m}{43200s}=0.0006541m\/s;"
Kinetic energy of needle movement:
"W_k=\\dfrac{mv^2}{2};"
"W_k=\\dfrac {160kg\\sdot( 0.0006541m\/s)^2}{2}=0.0000342J;"
Answer: "W_k=0.00003442J."
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