PART 1:

1. Why can't atoms be seen with a powerful optical microscope?

2. Why can atoms be seen with an electron beam?

3. What is the purposed of a model in science?

4. Where in the atom is most of the mass concentrated?

5. What is meant by the term nucleon?

6. How does the electric charge of a proton compare with the electric charge of an electron?

7.Since atoms are mostly empty space, why don't we fall through a floor we stand on?

8. How does one isotope differ from another?

9. Distinguish between mass number and atomic mass.

10. Which of the following are pure elements: H2,H2O, He, Na, NaCl , H2SO4, and U

11. A particular atom contains 29 electrons, 34 neutrons, and 29 protons. What is the identity of this element, and what is its atomic number?

12.If two protons and two neutrons are removed from the nucleus of an oxygen atom, what nucleus remains?

13. What happens to the volume of a loaf of bread that is squeezed? The mass? The density?

14. What is the mass density of water? What is the weight density of water?

15. What is Hooke's Law? Does it apply to elastic material or to inelastic materials?

16. If a 1-kg object stretches a spring by 2 cm, how much will the spring be stretched when it supports a 3-kg object? (Assume the spring does not reach its elastic limit.)

17. Why are the cross-sections of metal beams in the shape of the letter I instead of solid rectangles?

18. What is the volumes of a sugar cube that measures 1 cm on each side? What is the cross-sectional area of the cube? Total surface area?

19. A cube 2-cm on a side is cut into cubes 1-cm on a side.

• How many cubes result?

• What was the surface area of the original cube, ant what is the total surface area of the eight smaller cubes? What is the ratio of surface areas?

• Show that the surface-to-volume ratio of the smaller cube is twice as great as for the single larger cube.

20. What happens to the density of water when it freezes to become ice?

21. In a deep dive, a whale is appreciably compressed by the pressure of the surrounding water. What happen to the whale's density during the dive?

22. Which has more volume: a kilogram of gold or a kilogram of aluminum?

23. What is the relationship between liquid pressure and depth of liquid? Between liquid pressure and weight density?

24. Why does buoyant force act upward on the object submerged in water?

25. Fill in the blanks: An object denser than water will _________in water. An object less dense than water will ________in water. An object that has the same density as water will _________ in water.

26. Why do the gondolas of the Falkirk Wheel (see Figure 13.19) have the same weight whether or not they carry boats?

27. What geometrical shape has the smallest surface area for a given volume?

28. In lab you find that a 1-kg rock suspended above water weighs 10-N. When the rock is suspended beneath the surface of the water, the scale reads 8-N

a. What is the buoyant force on the rock?

b. If the container of water weight 10-N on the weighing scale, what is the scale reading when the rock is suspended beneath the surface of the water?

c. What is the scale reading when the rock is released and the rests at the bottom of the container?

29. Will a swimmer gain or lose buoyant force as she swims deeper in the water? Or will the buoyant force remain the same at greater depths? Defend your answer, and contrast it with your answer to the preceding question.

30. When an ice cube in a glass of water melts, does the water level in the glass rise, fall, or remain unchanged? Does your answer change if the ice cube has many air bubbles in it? How about if the ice cube contains many grains of heavy sand?

31. What is the energy source for the motion of gas in the atmosphere? What prevents atmospheric gases from flying off into space?

32. What is the cause of atmospheric pressure?

33. What is the mass of a cubic meter of air at room temperature (20oC)?

34. What is the approximate mass of a column of air 1-cm2 in area that extends from seal level to the upper atmosphere? What is the weight of this amount of air?

35. What is the pressure at the bottom of the column of air referred to in the preceding question?

36. Why won't a vacuum pump operate for a well that is deeper than 10.3 m?

37. What happens to the internal pressure in a fluid flowing in a horizontal pipe when its speed increases?

38. How does faster-moving above an airplane wing affect the pressure on the wing?

39. How does faster-moving water between two ships affect the water pressure against the sides of the ships?

40. On a perfect fall day, you are hovering at low altitude in a hot-air balloon, accelerated neither up or down. The total weight of the galloon, including its load and the hot aire in it, is 20,000 N.

a. Show that the weight of the displaced air is 20,000 N

b. Show that the volume of the displaced air is 1700 m3.