if the Uncompressed Gas in the Above System

Using Key Terms 2. (a) False. Matter is anything that has volume and mass. (b) False. Thermal contraction describes a substance getting smaller as its particles move closer together. Or: Thermal expansion describes a substance getting larger as its particles move farther apart . (c) False. Heat is the energy transferred from one type of matter to another as a result of a difference in temperature. (d) False. Sublimation is the change of state from solid directly to gas. Or: Melting is the change of state from solid to liquid. (e) True (f) True (g) False. Unbalanced forces cause a change in speed of an object. Or: A balanced force can keep an object stationary or moving at a constant speed and direction. (h) False. Compression is the decrease in volume produced by a force. (i) True (j) False. Pneumatics is the use of a gas in an enclosed system under pressure. Or: Hydraulics is the use of a liquid in an enclosed system under pressure. (k) True (l) False. The circulatory system is responsible for transporting oxygen and nutrients around the body. Or: The respiratory system is the set of organs and pathways involved in breathing. Checking Concepts 3. Thermal expansion is when matter expands as temperature increases. Thermal contraction is the decrease in volume of matter as temperature falls. 4. Thermal energy is the total amount of energy in a substance. 5. (a) Both are a change of state. (b) Melting is a change of state from solid to liquid. Evaporation is a change of state from liquid to gas. 6. Fresh water has a lower density than salt water. 7. D = M/V 8. Friction is a contact force that slows motion due to the rubbing of two surfaces. Magnetic force is an action-at-adistance force and can be a pushing or pulling force generated by natural and electromagnetic fields. 9. (a) Gas (b) Gases have a great deal of space between particles, so the particles can be forced together. Liquids do not have much space between particles, therefore they are incompressible by normal means. 10. Compression is a decrease in volume caused by a force. Deformation is a change in shape without a change in volume. 11. Viscosity is the resistance of a fluid to flow, while flow rate is the speed at which a substance flows from one point to another. 12. Increasing temperature decreases viscosity. Decreasing temperature increases viscosity. 13. The cohesive forces between particles of water form a tension on the water’s surface that is strong enough to hold up the bug. 14. This is largely due to gravity. Gravity pulls most of the air particles to the surface of Earth. With all the weight of the air above it, air at the surface is more compressed than the air at higher altitudes. This means there are fewer particles and less pressure as you increase in altitude. 15. Buoyant force is the upward force exerted by a fluid. 16. Static pressure is the result of a fluid under pressure. Even though it is not moving, it is capable of applying a force. 17. Hydraulic multiplication is used to increase force and transmit that force from one point to another. This is accomplished by using different sized pistons on separate ends of a contained liquid. 18. A hydraulic system uses a contained liquid, while a pneumatic system uses a contained gas (usually air). 19. A vacuum is an area where there is very low pressure. Understanding Key Ideas 20. According to kinetic molecular theory, the more energy particles have, the faster they move and farther apart they can get. Liquid water particles have more energy than particles in ice, therefore they move faster and are slightly farther apart. The particles in liquid water have enough energy and distance between each other to move past one another, while particles in ice do not. 21. Thick syrup has more particles, more tightly packed together, than does water. 22. Displacement is the amount of space that an object takes up when placed in a fluid. A larger ship takes up more space, so it could be said that a larger ship has a greater displacement. 23. (a) Gravity pulls the toboggan down, and friction works against its motion. (b) Gravity is an action-at-a-distance force; friction is a contact force. 24. Mass is the amount of matter in an object, and weight is the pull of gravity on an object. 25. (a) Balanced (b) The diagram should indicate four force arrows. Arrows forward and backward should be equal in size, indicating the force from the car forward, and friction backward. Arrows up and down should be equal in size, indicating the force of ground upward on the car, and the force of gravity down on the car. 26. Your elbow has a smaller surface area than your back. The smaller the area, the greater the pressure. 27. The shape of particles and their attraction for one another determines viscosity. If the particles of a substance are more complicated and/or more attracted to each other, they will not flow past each other as easily, which makes for greater viscosity. 28. Adhesion is the attraction of different particles to each other. The water particles are attracted to the glass, so they adhere to it. 29. As air is heated the particles move farther apart, so the air decreases in density. The lowdensity hot air rises, and cooler denser air (in this case, from above the water) rushes in to take its place. This is a convection current that is responsible for the cool breeze from the water. 30. The rust will interfere with the flow of water in the pipe. This reduction in flow reduces the efficiency of the hydraulic system. 31. Applying a force to uncompressed gas will simply make it compress. This is due to the relatively large amount of space between particles in gases. Once the gas has been compressed, and the particles forced together, the pressurized gas is now more capable of transmitting a force. 32. Contraction of blood vessels will cause an increase in blood pressure. As the blood vessels contract, there is less space for the blood to flow. This pushes the blood particles against the walls of the vessels with greater force every time the heart pumps, increasing pressure. Thinking Critically 33. (a) No, sand is not a liquid. Each individual sand grain is a solid and does not take the shape of its container. (b) Individual sand grains are the shape of cubes, reflecting the arrangement of particles in a solid. Solids have particles that move very little, and are stuck in position, which is why solids are unable to flow or take the shape of their container. 34. All these forces could appear in the diagram: • Arrow(s) down representing gravity’s pull on student and box. Equal arrow(s) up representing force of ground up on student/box. • Arrows in either direction of pull of rope indicating tension force. • Arrow backward on bottom of box indicating friction force. • Arrow forward at student representing force exerted forward. 35. (a) Thick steel is necessary to prevent being crushed by the great pressure at depth. (b) The great pressure could cause the vehicle to implode. 36. Heating such a can would cause the particles inside to gain energy and move faster. Normally, this would cause the particles to move farther apart, but since they are trapped in the can, the particles can only exert greater force against the inner walls of the can. This increases the pressure inside the can and could eventually make the can explode. 37. A hydraulic system would be more appropriate. Liquids transfer force more effectively than gases. By setting up a hydraulic multiplication system, motorcycles could be conveniently hoisted with the movement of a small piston with a moderate amount of force. 38. (a) If the drainage of the eye were blocked, it could cause a dangerous build-up of pressure in the eye. (b) If the production of fluid were interrupted, the internal pressure of the eye would drop. 39. It would be difficult for the circulatory system to function effectively without valves. Two of the major negative consequences would be: • The heart could not pump blood effectively. Valves in the heart prevent backflow of blood; without the valves, blood would swish back and forth ineffectively instead of moving from chamber to chamber and then out of the heart. • Blood would not flow in veins effectively. Valves in veins prevent backflow of blood: without valves, blood would return to the heart ineffectively. Developing Skills 40. (a) 0.9 g/mL (b) The density is less than water, so it would float. 41. The density of the substance is 7.87 g/cm3. The substance is iron. 42. (a) C (least), A (middle), B (greatest) (b) The diagram should show them layered from bottom to top: B, A, C. 43. 6666.7 Pa 44. 2133.3 Pa