Please take your time to answer these questions carefully!

3. Two spheres are cut from a certain uniform rock. One has V radius 4.50 cm. The mass of the other is five times greater. Find its radius.7. A crystalline solid consists of atoms stacked up in a repeat- ing lattice structure. Consider a crystal as shown in Fig- ure P].7a. The atoms reside at the corners of cubes of side L = 0.200 nm. One piece of evidence for the regular arrangement of atoms comes from the flat surfaces along which a crystal separates, or cleaves, when it is broken. Sup- pose this crystal cleaves along a face diagonal as shown in Figure P].7b. Calculate the spacing d between two adjacent atomic planes that separate when the crystal cleaves. Figure P13 9. Which of the following equations are dimensionally cor- rect? (a) v. = v. + ax (b) y = (2 m) cos (kx), where k = 2 m-116. An auditorium measures 40.0 m X 20.0 m X 12.0 m. The V density of air is 1.20 kg/m . What are (a) the volume of the room in cubic feet and (b) the weight of air in the room in pounds?\f