Question

There is a close "Big Ben" in London Fasting 60.0 kg, the long needle is 4.50 m long and weighs 100.0 kg. It has a rotating axis The kinetic love of love can go into circulation for an impossible two years. The left face is scaly Consider a long narrow rod with a distributed mass.

Answer 1

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: $W_k=0.00003442J.$