1.B

2. a) h=\(\dfrac{v^2}{2g}\)=\(\dfrac{30^2}{2.10}\)=45(m)

t=\(\dfrac{v}{g}\)=\(\dfrac{30}{10}\)=3(s)

b) S_2s=\(\dfrac{1}{2}\)gt_2s²=\(\dfrac{1}{2}\).10.2²=20(m)

\(\Delta S\)=S_3s-S_2s=h-S_2s=25(m)

\(\dfrac{\omega_1}{\omega_2}\)=\(\dfrac{T_2}{T_1}\)=60

\(\dfrac{v_1}{v_2}\)=\(\dfrac{\omega_1R_1}{\omega_2R_2}\)=60.1,5=90

\(\dfrac{a_{ht1}}{a_{ht2}}\)=\(\dfrac{\omega_1^2R_1}{\omega_2^2R_2}\)=60².1,5=5400