Which is more likely to hurt—being stepped on by a 200-lb man wearing loafers or by a 100-lb woman wearing high heels? Why?100 lB women wearing heels because her weight is concentrated into each heel and its more pressureWhy is it inaccurate to say that heavy objects sink and light objects float? Give exaggerated examples to support your answer.An object with sink or float depending on its density. A heavy log floats but a small rock will sink.Why will a steel razor blade carefully placed on the water surface not sink but a chunk of steel will sink?Surface tension accounts for floating.On a boat ride, the skipper gives you an extra-large life preserver filled with lead pellets. When he sees the skeptical look on your face, he says that you'll experience a greater buoyant force if you fall overboard than your friends wearing regular-sized Styrofoam-filled life preservers. Is he being truthful?He is being truthful, but you will drownWhat is the purpose of the ridges that prevent the funnel from fitting tightly in the mouth of a bottle?The ridges will allow air to escapeWhen an air bubble rises in water, what happens to its mass, volume, and density?The bubbles mass stays the same, the volume increases, the density decreasesA steel tank filled with helium gas doesn't rise in air, but a balloon containing the same helium rises easily. Why?An object only rises in air when buoyant force exceeds it's weight.High-speed water from a water cannon knocks people off their feet. Yet we're told that pressure within the high-speed water is low. Is this not a contradiction?Two balloons have the same weight and volume are filled with equal amounts of helium. One is rigid and the other is free to expand as the pressure outside decreases. When both balloons are released, discuss which will rise higher.The ballon that is free to expand will rise higherSilicon is the chief ingredient of both glass and semiconductor devices, yet the physical properties of glass are different from those of semiconductor devices. Explain.The structure is silicone may be more evident in one or the otherWhich is larger a celsius degree or a kelvinthey are the sameWhy does the pressure of gas enclosed in a rigid container increase as the temp increasesAs the temp is increased the molecules move faster and exert a greater pressureIf cooling occurred at the bottom of a pond instead of at the surface, would the pond freeze from the bottom up? Explain.No, ice forms at the bottom of the lake it will float to the topSteel plates are commonly attached to each other with rivets, which are slipped into holes in the plates and rounded over with hammers. The hotness of the rivets makes them easier to round over, but their hotness has another important advantage in providing a tight fit. What is it?When the rivets cool they contract, this tightens the plates being attachedIf you drop a hot rock into a pail of water, the temperatures of the rock and the water will change until both are equal. The rock will cool and the water will warm. Does this hold true if the hot rock is dropped into the Atlantic Ocean? Discuss.The hot rock will cool and the cool water will warm. If the rock is dropped into the atlantic the change in temp would be too small to measureIf you touch the metal sides inside of a hot oven with your bare hand, you're in trouble. But hold your hand briefly in the oven air and you're okay. What does this tell you about the relative conductivities of metal and air?Metal is very conductive, air is a poor conductorOn a very cold sunny day, you wear a black coat and a transparent raincoat. Which coat should be worn on the outside for maximum warmth?The transparent coat on the outsideBecause gloves do not generate heat, how do they keep your hands warm on a cold day?They have an insulating material that helps your body retain heat.Your friend states that the average speed of all hydrogen and nitrogen molecules in a container of gas is the same. Do you agree or disagree, and why?Disagree because hydrogen is lighterIs it important to convert temperatures to the Kelvin scale when we use Newton's law of cooling? Discuss why or why not.Either scale can be used because the diffrence is kelvins and celsius are the sameWhat is evaporation?The change of a liquid to a gasWhy does decreasing the temperature of a liquid make it freeze?When the temp is decreased motion is decreased which means less molecule seperation.Why does the temperature of boiling water remain the same as long as the heating and boiling continue?All of the heat energy provided is used up in changing the state of waterHow can water be brought to a boil without heating it?Increase the pressureCan ice be colder than 0°C?YesWhat is the lowest possible temperature on the Celsius scale? On the Kelvin scale?Lowest temp is -273C and 0KIf work is done on a system, does the internal energy of the system increase or decrease?IncreaseHow does the second law of thermodynamics relate to the direction of heat flow?Heat never of itself flows from cold object to hot objectThe temperature of the Sun's interior is about 15 million degrees. Is it important whether this is degrees Celsius or kelvins? Explain.It doesn't matterSuppose that you have a sturdy jar of helium gas with a temperature of 0°C. At what Celsius temperature will it be twice as hot (have twice the internal energy)?273CIf the speed of a wave doubles while the frequency remains the same, what happens to the wavelength?It doublesWhat kind of motion should you impart to a stretched Slinky to provide a transverse wave? To provide a longitudinal wave?Transverse wave: back and forth motion perpendicular to length of the pendulum
Longitudual: in and out motion parallel to the length of the slinkyWhy is there a Doppler effect when the source of sound is stationary and the listener is in motion? In which direction should the listener move to hear a higher frequency? A lower frequency?If you move toward a stationary source you encounter wave crests more frequently and the frequency of the recieved sound is higher. If you move away the wave crests encounter you less frequently.If the sound of an airplane does not appear to originate in the sky where it is seen, what does this say about the differences in the speeds of sound and light?You hear an airplane in a direction that differs from where you see it. Speed of light is faster than the soundIn Olympic competition, a microphone detects the sound of the starter's gun and sends it electrically to speakers at every runner's starting block. Why?The farthest person away from the gun would hear the gun later then the person closest. The speed of electricity os much faster then the speed of soundWhat two physics mistakes occur in a science fiction movie that shows a distant explosion in outer space, where you see and hear the explosion at the same time?There would be no sound of the explosion in space at all. If there was sound, you would see the explosion long befire you would hear itThe sitar, an Indian musical instrument, has a set of strings that vibrate and produce music, even though they are never plucked by the player. These "sympathetic strings" are identical to the plucked strings and are mounted below them. What is your explanation?The sound wave fromt he plucked string create a small force on the sympathetic string at the exact resonance and causing them to vibrateUltrasonic waves have many applications in technology and medicine. One advantage is that high intensities can be used without danger to the ear. Cite another advantage of their short wavelength. (Hint: Why do microscopists use blue light rather than white light to see detail?)The short wavelength of ultrasoinic waves undergo less diffraction and allow more detail to be seenIf sound becomes louder, which wave characteristic is likely increasing—frequency, wavelength, amplitude, or speed?AmplitudeWhy do the same notes on a trumpet and on a saxophone sound different when both are played with the same pitch and loudness?Each instrument produces a different set of harmonies or overtones at different intensitiesHow can you tune the note A3 on a piano to its proper frequency of 220 Hz with the aid of a tuning fork whose frequency is 440 Hz?You can use the tunning fork at 440 to tune it at 220The loudness of a radio is 40 dB. How loud would ten of these radios be?50dBCite a major difference between electrical and gravitational forces?Electrical forces can attract or repel whereas graviataional forces can only attractWhy does graviation between Earthy and the Moon predoimateThe force cancels because they have equal number of positive and negative chargesWhich part of an atom is positively charged, and which part is negatively charged?The nuclues and protons are postively charged the electrons are negatively chargeHow is Coulomb's law similar to Newton's law of gravitation? How is it different?Both laws are inverse square laws. They differ that gravitation is only attractive and elecreical froces repelWhy are metals good conductors both of heat and of electricity?Any metal is a good conductor because the outter atomic shells atoms are looseThe three pairs of metal same-size spheres have different charges on their surfaces, as indicated. Each pair is brought together, allowed to touch, and then separated. Rank from greatest to least the total amount of charge on the pairs of spheres after separation.A,C,BWhy is charge usually transferred by electrons rather than by protons?Electrons are loosely bonded on the outside whereas protons are very tightly bound within the atomic nucleiWhat does the inverse-square law tell you about the relationship between electric force and distance?Tells us that the force decreaes as the distance increasesStrictly speaking, when an object acquires a positive charge by the transfer of electrons, what happens to its mass? Discuss what happens to its mass when it acquires a negative charge. (Think small!)If postive charge it will loose electrons and its mass. If negatively charged it will gain electrons and increase in massIt is relatively easy to strip the outer electrons from a heavy atom like that of uranium (which then becomes a uranium ion), but it is very difficult to remove the inner electrons. Discuss why this is so.The further away the weaker the attraction.What condition is necessary for the flow of heat? What analogous condition is necessary for the flow of charge?Heat must have a difference in temperature. Flow of charge must have a differnce in eletrical potentialWill water flow more easily through a wide pipe or a narrow pipe? Will current flow more easily through a thick wire or a thin wire?Water will flow more quickly through a wide pipe. Current flow will move more easy through a thick wireHow does wetness affect the resistance of your body?The salt left from perspiration when wet lowers our skin resistant to a few hundred ohms or lessRank the circuits illustrated according to the brightness of the identical bulbs, from brightest to dimmest.A=B=CAll bulbs are identical in the circuits shown. An ammeter is connected next to the battery, as shown. Rank the current readings in the ammeter, from greatest to least.C,B,AAre automobile headlamps wired in parallel or in series? What is your evidence?The headlights are wired in parallel. When one headlight is out the other still works.What is the source of magnetic force?Moving electronsWhat is the difference between an unmagnetized iron nail and a magnetized iron nail at the micro level?In unmagnetized the magnetic domain hav random orietnation so the net megnetism adds to zero. In a magnetized nail many of the megnetic domains are alignedIf you drop an iron magnet on a concrete sidewalk it will become a weaker magnet. Why?Vibrations provide energy to randominze the magentic direction of the domainsWhy is it inadvisable to make a horseshoe magnet from a flexible material? .The poles of the magent attract each other and will cause the magnet to bend enough for the poled to touch.While a paper clip is in a magnetic field it can attract other paper clips. Why does the paper clip continue to attract once the magnetic field is removed?The alignement persists for awhile so that when removen from the inital magnetic source residual magnetism persists.What is the principal difference between a radio wave and visible light? Between visible light and an X-ray?FrequencyWhat is the color of the lowest frequency of visible light? Of the highest frequency?Lowest: red
Highest: violetHow do the rods in the eye differ from the cones?Rods are responsible for vsion at low light levels. Cones are responsible for vision at higher levels.When you look at a distant galaxy through a telescope, are you looking backward in time?You are seeing the delay of light reach your eyeAre the wavelengths of radio and television signals longer or shorter than waves detectable by the human eye?Both are much longer because their frequencies are much lower thatn the frequencies of visible light.Which has the higher frequency, red light or blue light?BlueWhat color of light is produced by the combination of equal intensities of red light and cyan light?White lightDo the feathers of blackbirds reflect black, or absorb light in general?AbsorbGreen + blue = cyan = white - _______RedWhy is red paint red?It absorbs all wave links of the visible light spectrum.
