Radiation machines used to treat tumors produce an intensity of radiation that varies inversely as the square of the distance from the machine. At 3 meters, the radiation intensity is 62.5 milliroentgens per hour. What is the intensity at a distance of 1.9 meters? The intensity is tenth as needed.)

1. Если бы можно было уложить в один ряд вплотную друг к другу 10000000 молекул воды \( (\mathrm{d}=0,3 \) нм), то получилась бы ниточка длиной... 1. 3 m . 2. 300 cm . 3. \( 0,003 \mathrm{~m} \). 4. 3 дм.

65 Sui piatti di una bilancia a bracci ugua- li vengono posti \( 15 \mathrm{~cm}^{3} \) di vetro \( (d=2,5) \) e \( 120 \mathrm{~cm}^{3} \) di sughero \( (d=0,25) \). Quanti grammi di sughero si dovranno aggiungere per stabilire l'equilibrio? \( [7,5 \mathrm{~g}] \)

\( vf=vi+a.t \)

\( vf=vi+a.t \)

6) A 70 kg man steps onto a scale inside an elevator. What does the scale read if the elevator descends while slowing down at a rate of \( 3 \mathrm{~m} / \mathrm{s}^{2} \) ? a. 49 kg b. 70 kg c. 82 kg d. 91 kg