R1=2R2
T1=60 мин
Т2=12 ч=720 мин

$a= \frac{ v^{2} }{R}$

$v= \frac{2 pi R}{T}$

$a= \frac{4 pi ^{2}R}{T}$

$\frac{ a_{2} }{ a_{1} } = \frac{4 pi ^{2} R_{2} T_{1} }{ T_{2} 4 pi ^{2} R_{1} } = \frac{R_{2} T_{1}}{T_{2} R_{1}} = \frac{2R_{1}60}{720R_{1}} = \frac{120}{720}$

$\frac{ a_{1} }{ a_{2} }= \frac{720}{120}= 6$