Fundamentals of Physics Exam 3 | Complete Solutions (Verified)

Fundamentals of Physics Exam 3 | Complete Solutions (Verified) If you triple the diameter of a ball, the volume of the ball will be: 27x larger Arches work well in construction because ________. a. The entire structure is under tension b. The entire structure is under compression c. The compression and tension balance each other out. If you have two differently-sized spheres of metal and they have the same mass, then ________. a. The smaller sphere is denser b. Their densities are proportional to their sizes c. The larger sphere is denser d. They have the same density as well An elastic material is one that___. a. Keeps its new shape once deformed b. Bends at least somewhat before breaking c. Is relatively easy to deform. d. Returns to its original shape after being deformed. Compared to smaller animals, larger animals have a ________. a. similar ratio of surface area to weight b. smaller ratio of surface area to weight c. larger ratio of surface area to weight d. The pressure under 100 feet of salt water is closest to ________. The pressure under 100 ft of saltwater is closest to: a. 45 PSI b. 3 atm c. 20,000 leagues d. 400kPa When a boat is floating in the water, ________. a. the buoyant force is greater than the weight of the boat b. the buoyant force equals the mass of the boat c. the buoyant force equals the weight of the boat d. the volume of displaced water equals the volume of the boat Pressure can be increased by ________. a. increasing the area or decreasing the force b. taking more time to relax c. raising both the force and the area by proportional amounts d. increasing the force or decreasing the area In a hydraulic press (hydraulic lever), if the force is multiplied by a factor of 20, ________. a. the pressure is also multiplied by a factor of 20 b. the distance is divided by a factor of 20 c. the distance is also multiplied by a factor of 20 d. the product of force x distance is also multiplied by 20 If a tire pressure gauge reads 30 PSI, the actual absolute pressure in the tire is closest to ________. a. 150 kPa b. 45 PSI c. 90 mmHg d. 15 PSI If the pressure in a gas is multiplied by a factor of 6 and the temperature is multiplied by a factor of 3, the volume of the gas will be ________ the original volume. a. three times b. twice c. one half of d. one third of Bernoulli's Principle states that, as the velocity of a fluid increases, ________. a. the temperature of the fluid will also increase b. the volume of the fluid will decrease c. the pressure in the fluid will decrease d. the pressure in the fluid will also increase In a plasma, the ________. a. atoms are broken down into molecules b. protons are separated from the neutrons c. electrons are separated from the nuclei d. isotopes are separated by charge Ninety nine percent of our atmosphere is contained in a layer about ________ thick. a. 30 miles b. 10 miles c. 40 miles d. 20 miles Density of atmosphere- KE of molecules= tend to disperse, while gravity pulls them down near earth Earth's atmosphere is composed primarily of ________. 78% Nitrogen 21% O 9% Ar .04% CO2 Do all materials expand when heated? No. One example is water Compared to an increase in temperature of 20 Fahrenheit degrees, an increase in temperature of 20 Celsius degrees is ________. a. the same b. smaller c. larger A material with a low specific heat will tend to ________. a. cool down quickly but heat up slowly b. heat up and cool down quickly c. heat up quickly but cool down slowly d. heat up and cool down slowly Compared to a cup of hot coffee, a bathtub full of lukewarm water has ________. a. lower internal energy and lower average molecular energy b. higher average molecular energy but lower internal energy c. higher internal energy but lower average molecular energy d. higher internal energy and higher average molecular energy internal energy= sum of all energies- bigger = more- KE, PE, etc. molecular is heat energy, average speed of molecules Heat is defined as ________. the flow of energy from a higher temperature object to a lower temperature object The lower the temperature of an object, the ________ the wavelength of electromagnetic radiation it emits Longer If a window is perfectly sealed (no air leaks), heat can still penetrate via ________. conduction and EM radiation If you touch a wooden pencil and a metal pen that have both been sitting on your desk, the pen feels cooler because ________. the metal is a better heat conductor than wood The longer the wavelength of electromagnetic radiation, the ________ the frequency. lower higher frequency = shorter wavelength Global warming due to the Greenhouse Effect ________ . a. was first discovered by Al Gore in the early 1970's b. is a Chinese hoax designed to take away our jobs c. may actually be due to ash and other contaminants from volcanos d. can happen on any planet with an atmosphere When water vapor condenses into liquid water, it ________. a. must pass through a solid phase b. transfers heat to the liquid water with no net heat flow to the environment c. absorbs heat from the environment d. releases heat to the environment Clouds and fog are caused by ________. a. evaporating liquid water b. burning too many fossil fuels c. condensing water vapor d. vapor deposition in the atmosphere In a standard air conditioner or heat pump, the refrigerant ________ outside and ________ inside. condenses, evaporates In a pressure cooker, the food is cooked faster than in a normal pot because ________. a. the increased pressure breaks down the food molecules faster b. the water boils at a higher temperature c. the lower pressure breaks down the food molecules faster d. the water boils at a lower temperature In a standard refrigerator, it is the ________ that is most responsible for the transfer of heat. a. latent heat of refrigeration b. latent heat of fusion c. latent heat of vaporization d. latent heat of sublimation Absolute zero is approximately ________ -273 Celsius, 0 Kelvin, -459.67 Fahrenheit the lowest possible temperature that a substance may have- their temperature at which molecules of the substance have their minimum kinetic energy. no more energy can be extracted, cannot be cooler Normal room temperature is closest to ________. 300 Kelvin, 20-22 C, 68- 72 F When a gas is compressed, ________. a. its internal energy will decrease b. its internal energy will increase c. the gas will expand d. internal energy will flow out of the gas If heat flows into a system, ________. a. the system will be able to do more work b. the system will be able to do less work c. the work capacity of the gas is not affected What/ where is the neutral layer in a beam that supports a load? The region of neither tension nor compression when supporting a load; the middle portion of the beam. If the linear dimensions of an object are doubled, by how much does the surface area increase? By how much does the volume increase? (scaling) SA increases by 4, volume increases by 8 Why can small creatures fall considerable distances without injury while people need parachutes to do the same? Small creatures have a larger surface area relative to body weight, and they encounter greater air resistance relative to body weight, resulting in a slower fall than that of larger creatures Where do tension and compression occur? for horizontal beams, compression at the top, tension at the bottom; stretched= tension, squashed= compression; vertical beams = compressed; I- beam use? it is like a solid bar with some of the steel scooped from the middle, where it is needed the least. Beam is lighter but has the same strength. density mass of a substance per unit volume. d=m/v weight density = weight/v Hooke's Law the amount of stretch or compression of an elastic material is directly proportional to the applied force: f~Δ(x) k = spring constant F= kΔx F (N) force x (m) length it changes k (n/m) constant how easy it is to stretch and compress ex. im 70 kg i sit on a spring it compresses 2cm. Constant? weight= (70kg)(10m/s) 2cm= .02m F=kx 700N=k(.02m) = 35,000 N/m pressure the ratio of force to the area over which that force is distributed P=F/a = Pa; 1Pa= 1 N/m^2 at sea level 1 atm= 101,325 Pa= 101.3 kPa= 14.7 PSI = 760 mmHg = 29.9 inHg liquid pressure= weight density * depth buoyant force the net upward force that a fluid exerts on an immersed object. Acts upward on an object due to greater pressure at greater depth. When an object floats, its buoyant force equals its weight- buoyant force equals both the weight of the object and the weight of the water it displaced; a floating object displaces a weight of fluid equal to its own weight; buoyancy makes a hot air balloon rise- hot air is less dense than the cool air around it archimedes principle an immersed body is buoyed up by a force equal to the weight of the fluid it displaces; m helium balloon ascending- if free to expand as it rises, it will increase vol and decrease density to keep rising- they usually expand a little then settle where the buoyancy matcher the weight principle of flotation a floating object displaces a weight of fluid equal to its own weight Pascal's principle the pressure applied to a motionless fluid confined in a container is transmitted undiminished throughout the fluid; makes hydraulic lever work when force is multiplied while distance is divided surface tension the tendency of the surface of a liquid to contract in area and thus to behave like a stretched elastic membrane capillarity the rise of a liquid in a fine, hollow tube or in a narrow space atmospheric pressure the pressure exerted against bodies immersed in the atmosphere, It results from the weight of the air pressing down from above. At sea level. atmospheric pressure it about 101 kPa. barometer measures atmospheric pressure Boyle's Law the product of pressure and vol is a constant for a given mass of confined gas, as long as the temperature remains unchanged P1V1=P2V2 P= 1/V pressure and volume inversely proportional double one = half the other Archimedes principle (air) an object in the air is buoyed up with a force equal to the weight of the displaced air Bernoulli's principle where the speed of a fluid increases, the internal pressure in the fluid decreases; for airplanes- the wind design causes air to flow faster over the top and slower underneath, causing the high under pressure to lift it; higher pressure inside house causes the roof to blow off in a storm; higher velocity lower pressure plasma an electrified gas that contains ions and free electrons. most of the matter in the universe is in the plasma phase; electrons and nuclei are separated; Most plasmas are created when extra energy is added to a gas, knocking electrons free from atoms. High temperatures often cause plasmas to form. Atoms in a hot gas are moving so fast that when they collide with each other they sometimes knock electrons loose. temperature a measure of the average translational kinetic energy per molecule in a substance. heat the energy that flows from a substance of higher temp to a substance of lower temp, usually measured in calories or joules internal energy the total of all molecular energies, kinetic plus potential, that are internal to a substance. specific heat capacity the quantity of heat per unit mass required to raise the temperature of a substance by 1 degree C Q = mcΔT Q = quantity of heat transferred heat energy (Joules, J) m = mass of a substance (kg) c = specific heat capacity (units J/kg∙K) ΔT = change in temperature (Kelvins, K) specific heat = quantity of heat/ gram degree C scaling as an object gets larger, it has less surgace area compared to volume; chipmunk has more skin area per lb than an elephant; more surface area = can react w surroundings better; 2x length= 4x surface area= 8x vol and weight Brownian motion random microscopic movement of atoms in liquid or gas- responsible for dispersion and atmospheric pressure actual pressure from a pressure gauge? Pressure read in a pressure gauge does not include atmospheric pressure- the actual pressure you have to add 1 atm (14.7 PSI) Pressure under water pressure at surface + pressure of water P= Po+pgh Po= pressure at surface 101.3kPa p= density of fluid (kg/m3) g= gravity = 10 m/s2 h= depth (m)