Complete the following statements related to the law of universal gravitation. Read the beginning of each statement and match it with one of the phrases at the bottom to complete it correctly. "The reason the Moon's gravity affects the Earth more than Jupiter's does, even though the Moon has a smaller mass, is because" The larger object will have a greater gravitational force The force due to gravity will be less Inversely proportional. The distance is less.

7.2 A beam of light travels from water to plastic. The speed of light in plastic is \( 2,05 \times 10^{8} \mathrm{~m} \cdot \mathrm{~s}^{-1} \). The refractive index of water is 1,33 . Calculate the refractive index of plastic.

8.4 To produce an emf of 9 V , the area of the coil, with its axis coinciding with the direction of a magnetic field (area perpendicular to magnetic field), is halved in 2 minutes from \( 0.6 \mathrm{~m}^{2} \) to \( 0,3 \mathrm{~m}^{2} \). Calculate the number of turns around the coil.

157. Una bombola a pareti rigide di 30 L contiene \( 0,5 \mathrm{moli} \) di un gas perfetto biatomico alla temperatura iniziale di \( 20^{\circ} \mathrm{C} \). Essa viene tenuta sotto il sole per un certo tem- po e si nota che la temperatura finale è di \( 80^{\circ} \mathrm{C} \). Trascu- rando la dilatazione termica della bombola, si calcoli: - il lavoro fatto dal gas; - la variazione di pressione del gas; - la variazione di energia interna del gas. [0 J; \( \left.8,3 \times 10^{3} \mathrm{~Pa} ; 6,2 \times 10^{2} \mathrm{~J}\right] \) (Esame di Fisica, Corso di laurea in Farmacia, Università La Sapienza di Roma, 2006/2007)

3. Si un ratón y un elefante comen ambos con la misma energía cinética, ¿podrías decir cuál corre más aprisa? Explica tu respuesta en términos de la ecuación de la ECT?

3) Choose the correct alternative and rewrite the statement (i) The weight of a body on the earth's surface \( =\ldots \ldots . \). \( \begin{array}{llll}\text { (a) } \frac{G M m}{R} & \text { (b) } \frac{G M m}{R^{2}} & \text { (c) } G M m R^{2} & \text { (d) } \frac{G m}{R^{2}}\end{array} \)