Q&A Hero

Q: Over a short interval near time t = 0 the coordinate of an automobile in meters is given byx(t) = 27t - 4.0t3, where t is in seconds. At the end of 1.0 s the acceleration of the auto is:A) 23 m/s2B) 15 m/s2C) -4.0 m/s2D) -12 m/s2E) -24 m/s2

Q: A ball rolls up a slope. At the end of three seconds its velocity is 20 cm/s; at the end of eight seconds its velocity is 0 cm/s. What is the magnitude of its average acceleration from the third to the eighth second? A) 2.5 cm/s2 B) 4.0 cm/s2 C) 5.0 cm/s2 D) 6.0 cm/s2 E) 6.67 cm/s2

Q: What is the relationship between instantaneous speed and instantaneous velocity? A) They are identical. B) Instantaneous speed is the rate at which the instantaneous velocity is changing. C) Instantaneous speed is the magnitude of the instantaneous velocity. D) They are unrelated. E) Instantaneous speed is the initial speed minus the final speed.

Q: The coordinate-time graph of an object is a straight line with a positive slope. The object has: A) constant displacement B) steadily increasing acceleration C) steadily decreasing acceleration D) constant velocity E) steadily increasing velocity

Q: This graph shows the position of a particle as a function of time. What is its instantaneous velocity at t = 7s? A) 3 m/s B) -3 m/s C) 12 m/s D) -12 m/s E) Need additional information.

Q: Which of the following five coordinate versus time graphs represents the motion of an object moving with a constant nonzero speed? A) I B) II C) III D) IV E) V

Q: The coordinate of an object is given as a function of time by x = 7t " 3t2, where x is in meters and t is in seconds. Its velocity at t = 3s is: A) -6 m/s B) -11 m/s C) -21 m/s D) 9 m/s E) 18 m/s

Q: Each of four particles moves along an x axis. Their coordinates (in meters) as functions of time (in seconds) are given byparticle 1: x(t) = 3.5 - 2.7t3particle 2: x(t) = 3.5 + 2.7t3particle 3: x(t) = 3.5 + 2.7t2particle 4: x(t) = 3.5 - 3.4t - 2.7t2For which of these particles is the velocity increasing for t> 0?A) All fourB) Only 1C) Only 2 and 3D) Only 2, 3, and 4E) None of them

Q: The coordinate of a particle in meters is given by x(t) = 16t - 3.0t3, where the time t is in seconds. The particle is momentarily at rest at t =A) 0.75 sB) 1.3 sC) 1.8 sD) 5.3 sE) 7.3 s

Q: This graph shows the position of a particle as a function of time. What is its average velocity between t = 5s and t = 9s? A) 3 m/s B) -3 m/s C) 12 m/s D) -12 m/s E) Need additional information.

Q: Which of the following five coordinate versus time graphs represents the motion of an object whose speed is increasing? A) I B) II C) III D) IV E) V

Q: You leave your house and drive to your friend's house, where you stay a while. Then you come back home. Which of the following must be true of your trip? A) Your instantaneous velocity was never zero. B) Your average velocity was zero. C) Your acceleration was constant. D) Your net displacement was not zero. E) Your average speed was zero.

Q: A car starts from Hither, goes 50 km in a straight line to Yon, immediately turns around, and returns to Hither. The time for this round trip is 2 hours. The average speed of the car for this round trip is: A) 0 km/h B) 25 km/h C) 50 km/h D) 100 km/h E) cannot be calculated without knowing the acceleration

Q: A car travels 40 kilometers at an average speed of 80 km/h and then travels 40 kilometers at an average speed of 40 km/h. The average speed of the car for this 80 km trip is: A) 40 km/h B) 45 km/h C) 53 km/h D) 60 km/h E) 80 km/h

Q: Two automobiles are 150 kilometers apart and traveling toward each other. One automobile is moving at 60 km/h and the other is moving at 40 km/h. In how many hours will they meet? A) 2.5 h B) 2.0 h C) 1.75 h D) 1.5 h E) 1.25 h

Q: The average speed of a moving object during a given interval of time is always: A) the magnitude of its average velocity over the interval B) the distance covered during the time interval divided by the time interval C) one-half its speed at the end of the interval D) its acceleration multiplied by the time interval E) one-half its acceleration multiplied by the time interval.

Q: The position y of a particle moving along the y axis depends on the time t according to the equation y = at " bt2. The dimensions of the quantities a and b are respectively: A) L2/T, L3/T2 B) L/T2, L2/T C) L/T, L/T2 D) L3/T, T2/L E) none of these

Q: The coordinate of an object is given as a function of time by x = 7t - 3t2, where x is in meters and t is in seconds. Its average velocity over the interval from t = 0 to t = 2 s is:A) 5 m/sB) -5 m/sC) 11 m/sD) -11 m/sE) 1 m/s

Q: A car starts from Hither, goes 50 km in a straight line to Yon, immediately turns around, and returns to Hither. The time for this round trip is 2 hours. The magnitude of the average velocity of the car for this round trip is: A) 0 km/hr B) 50 km/hr C) 100 km/hr D) 200 km/hr E) cannot be calculated without knowing the acceleration

Q: A particle moves from point x1 to point x2. Its displacement is given by:A) x2 - x1B) x1- x2C) x1 + x2D) x1E) x2

Q: A particle moves along the x axis from xi to xf . Of the following values of the initial and final coordinates, which results in a negative displacement?A) xi = 4m, xf = 6mB) xi = -4m, xf = -8mC) xi = -4m, xf = 2mD) xi = -4m, xf = -2mE) xi = -4m, xf = 4m

Q: A particle moves along the x axis from xi to xf . Of the following values of the initial and final coordinates, which results in the displacement with the largest magnitude?A) xi = 4m, xf = 6mB) xi = -4m, xf = -8mC) xi= -4m, xf = 2mD) xi = 4m, xf = -2mE) xi = -4m, xf = 4m

Q: When can you treat a moving object as if it were a point-like particle? A) Only if it really is a point-like particle. B) You can always treat a moving object as if it were a point-like particle. C) Only if the object is moving with constant acceleration. D) Only if all parts of the object are moving in the same direction and at the same rate. E) This question has no physical meaning.

Q: Suppose A= BnCm, where Ahas dimensions LT, Bhas dimensions L2T-1, and Chas dimensions LT2. Then the exponentsnand mhave the values:A) 2/3; 1/3B) 2; 3C) 4/5; -1/5D) 1/5; 3/5E) 1/2; 1/2

Q: Suppose A= BC, where Ahas the dimensionsL/M and Chas the dimensionsL/T. Then Bhas the dimension: A) T/M B) L2/TM C) TM/L2 D) L2T/M E) M/L2T

Q: During a short interval of time the speed vin m/s of an automobile is given by v= at2+ bt3, where the time tis in seconds. The units of a and bare respectively:A) m/s2; m/s4B) s3/m; s4/mC) m/s2; m/s3D) m/s3; m/s4E) m/s4; m/s5

Q: A sphere has a radius of 21 cm and a mass of 1.9 kg. Its mass density is about:A) 4.9x10-5kg/m3B) 2.1 x10-4kg/m3C) 2.0 x10-2kg/m3D) 16 kg/m3E) 49 kg/m3

Q: The unit of mass density might be: A) pound per cubic foot B) gram per liter C) kilogram per meter D) cubic kilogram per meter E) cubic meter per kilogram

Q: Two girders are made of the same material. Girder A is twice as long as girder B and has a cross-sectional area that is twice as great. The ratio of the mass density of girder A to the mass density of girder B is: A) 4 B) 2 C) 1 D) 1/2 E) 1/4

Q: One tonne (metric ton) is 1000 kg. How many grams are there in one tonne? A) 10-6 B) 10-3 C) 1 D) 103 E) 106

Q: If 1 u = 1.66 x 10-27kg, 1 gram = A) 1.66 x 10-24u B) 1.66 x 1024u C) 1.66 x 1027u D) 6.02 x 1026u E) 6.02 x 1023u

Q: Which of the following weighs about a pound on Earth? A) 0.05 kg B) 0.5 kg C) 5 kg D) 50 kg E) 500 kg

Q: Metric time is defined so that one day equals 10 hours; one hour equals 100 minutes; and one minute equals 100 seconds. One metric second equals how many normal seconds? A) 0.60 B) 0.864 C) 1.00 D) 1.16 E) 1.67

Q: Six million seconds is approximately: A) One day B) Ten days C) Two months D) One year E) Ten years

Q: The SI standard of time is based on: A) the daily rotation of the Earth B) the frequency of light emitted by Kr86 C) the yearly revolution of the Earth about the sun D) a precision pendulum clock E) none of these

Q: 1.513 + 27.3 = A) 29 B) 28.8 C) 28.9 D) 28.81 E) 28.813

Q: 3.2 x 2.7 =A) 9B) 8C) 8.6D) 8.64E) 8.640

Q: The number of significant figures in 15.0 is: A) 1 B) 2 C) 3 D) 4 E) 5

Q: The number of significant figures in 0.00150 is: A) 2 B) 3 C) 4 D) 5 E) 6

Q: Which of the SI standard units is NOT based on a constant of nature? A) The meter, because the speed of light can vary from place to place. B) The second, because cesium cannot be found everywhere. C) The kilogram, because it is based on an arbitrary piece of metal. D) The kilogram, because the gram is the standard unit. E) The meter, because it is defined in terms of the speed of light in vacuum, and there is no perfect vacuum anywhere.

Q: The SI standard of length is based on: A) the distance from the north pole to the equator along a meridian passing through Paris B) wavelength of light emitted by Hg198 C) wavelength of light emitted by Kr86 D) a precision meter stick in Paris E) the speed of light

Q: A square with an edge of exactly 1 cm has an area of:A) 10-6m2B) 10-4m2C) 10-2m2D) 102m2E) 104m2

Q: A cubic box with an edge of exactly 1 cm has a volume of:A) 10-9m3B) 10-6m3C) 10-3m3D) 103m3E) 106m3

Q: A right circular cylinder with a radius of 2.3 cm and a height of 1.4 cm has a total surface area of:A) 1.7 x10-3m2B) 3.2 x10-3m2C) 2.0 x10-3m2D) 5.3 x10-3m2E) 7.4 x10-3m2

Q: A right circular cylinder with a radius of 2.3 cm and a height of 1.4 m has a volume of:A) 23 m3B) 0.23 m3C) 9.3 x10-3m3D) 2.3 x10-3m3E) 7.4 x10-4m3

Q: A sphere with a radius of 1.7 cm has a surface area of:A) 2.1 x10-5m2B) 9.1 x10-4m2C) 3.6 x10-3m2D) 0.11 m2E) 36 m2

Q: A sphere with a radius of 1.7 cm has a volume of:A) 2.1 x10-5m3B) 9.1 x10-4m3C) 3.6 x10-3m3D) 0.11 m3E) 21 m3

Q: 1 m is equivalent to 3.281 ft. A cube with an edge of 1.5 ft has a volume of:A) 1.2 x102m3B) 9.6 x10-2m3C) 10.5 m3D) 9.5 x10-2m3E) 0.21 m3

Q: There is no SI base unit for area because: A) an area has no thickness; hence no physical standard can be built B) we live in a three (not a two) dimensional world C) it is impossible to express square feet in terms of meters D) area can be expressed in terms of square meters E) area is not an important physical quantity

Q: Which of the following is closest to a yard in length? A) 0.01 m B) 0.1 m C) 1 m D) 100 m E) 1000 m

Q: In 1866, the U. S. Congress defined the U. S. yard as exactly 3600/3937 international meter. This was done primarily because: A) length can be measured more accurately in meters than in yards B) the meter is more stable than the yard C) this definition relates the common U. S. length units to a more widely used system D) there are more wavelengths in a yard than in a meter E) the members of this Congress were exceptionally intelligent

Q: 1 mi is equivalent to 1609 m so 55 mph is: A) 15 m/s B) 25 m/s C) 81 m/s D) 123 m/s E) 1500 m/s

Q: A gram is:A) 10-6kgB) 10-3kgC) 1 kgD) 103kgE) 106kg

Q: A nanosecond is:A) 109sB) 10-9sC) 10-6sD) 10-15sE) 10-12s

Q: The SI base unit for mass is: A) gram B) pound C) kilogram D) ounce E) kilopound

Q: The SI base units have the dimensions of: A) mass, weight, time B) length, density, time C) mass, length, time D) weight, length, time E) mass, length, speed

Q: (7.0 x106)/(2.0 x10-6) =A) 3.5 x10-12B) 3.5 x10-6C) 3.5D) 3.5 x106E) 3.5 x1012

Q: 5.0 x105+ 3.0 x106=A) 8.0 x105B) 8.0 x106C) 5.3 x105D) 3.5 x105E) 3.5 x106

Q: (5.0 x104) x(3.0 x 10-6) =A) 1.5 x10-3B) 1.5 x10-1C) 1.5x101D) 1.5 x103E) 1.5x105

Q: (5.0 x104)x(3.0 x106) =A) 1.5 x109B) 1.5 x1010C) 1.5 x1011D) 1.5 x1012E) 1.5 x1013

Q: It currently appears that within this universe we have mostly A) neutrinos. B) matter. C) dark matter. D) dark energy.

Q: If heat death results in a maximum amount of entropy, then what does this say about entropy at the beginning of the universe? A) Entropy at the beginning of the universe must also have been at a maximum. B) There was a change in the direction of entropy flow about 7 billion years ago. C) The Big Bang was a moment of minimal entropy. D) Nothing.

Q: Eternal Inflation refers to A) the possibility that our universe is only a patch of a greater universe and that the process of universe spawning will continue forever. B) the observation that cosmic inflation could eventually curve back in on itself, causing its opposite: the compression of space. C) cosmic inflation inflating itself such that its own inflation is self-generating. D) the presence of a distinct beginning of time.

Q: The Big Rip refers to the A) accelerating influence of dark energy, causing all matter to become completely ripped apart. B) phenomenon of dark energy causing the universe to rip into multiple spacetimes. C) possibility that galactic centers may suddenly implode causing galactic disintegration. D) phenomenon of dark energy decelerating, causing all matter to disintegrate.

Q: Heat death refers to the universe A) reaching the lowest energy state possible, which will mean the greatest level of entropy. B) ending after a massive fire. C) reaching a state where all stars expand and merge into each other. D) reaching the point where the process of radioactive decay is no longer possible.

Q: The modern theory of dark energy arises from observations showing that A) galaxies spin at slower than expected rates. B) superclusters are collapsing. C) the speed of light is not exactly constant. D) galaxies are accelerating away from each other.

Q: The theory of dark energy tells us that A) empty space is seething with a form of energy. B) there is a force that behaves like an anti-gravity. C) there is still much to learn about this universe. D) All of the above.

Q: Distant galaxies are A) growing closer to each other as they encounter the curvature of the universe. B) accelerating away from each other. C) slowing in their dispersal due to the effects of gravity. D) connected to each other by dark energy.

Q: Dark energy bends the curvature of spacetime A) in the exact same fashion as gravity. B) in the opposite manner of gravity. C) by absorbing all lightwaves that pass through it. D) dark energy does not bend the curvature of spacetime.

Q: Dark energy A) is the phenomenon responsible for the acceleration of the universe. B) would be considered to be the opposite of gravity. C) is energy that exerts an outward pressure, causing spacetime to expand. D) All of the above

Q: Where is dark matter found in the periodic table? A) within the noble gas elements B) the transition metals C) all radioactive elements D) no where at all

Q: If dark matter were to be found on this planet it would likely be A) high in our atmosphere. B) within our oceans. C) within Earth's mantle. D) at the center of Earth's core.

Q: According to dark matter theory, most of the mass of a spiral galaxy is found A) within the central supermassive black hole. B) within the luminescent spiral arms. C) outside of the luminescent spiral arms. D) in the form of dark energy.

Q: Evidence for dark matter is exhibited by the A) relatively similar speeds at which all stars in a galaxy orbit the galactic nucleus. B) speed at which galaxies orbit one another within clusters. C) degree to which galaxy clusters exhibit gravitational lensing effects. D) All of the above

Q: Dark Matter is matter that A) cannot be seen, felt, or measured. B) cannot be seen or felt, but can be measured through its gravitational effects. C) is Dark Energy's complement. D) is found within a black hole.

Q: A four dimensional image of a coffee table is depicted in a A) tesseract. B) video. C) photograph. D) hologram.

Q: According to special relativity, two events that occur simultaneously in one frame of reference A) are also simultaneous in all frames of reference. B) can be non-simultaneous in another frame of reference. C) is evidence for the constant speed of light. D) are in reality non-simultaneous.

Q: As a blinking light source approaching you gains speed, you see the frequency of flashes A) increase. B) decrease. C) remain unchanged. D) None of these.

Q: If you were to travel at a speed close to the speed of light, you would notice that your own A) mass changes. B) pulse decreases. C) Both of these. D) Neither of these.

Q: Clocks on fast-moving spaceship shizzing past Earth appear to run slow when viewed from A) inside the spaceship. B) Earth. C) Both of these. D) Neither of these.