| № |
Condition |
free/or 0.5$ |
| 55603 | A person walks first at a constant speed of 5.00 m/s along a straight line from point A to point B and then back along the line from B to A at a constant speed of 3.00 m/s.
What is
(a) Her average speed over the entire trip?
(b) Her average velocity over the entire trip? |
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| 55604 | A perfectly plane house roof makes an angle - with the horizontal. When its temperature changes, between Tc before dawn each day to Th in the middle of each afternoon, the roof expands and contracts uniformly with a coefficient of thermal expansion α1. Resting on the roof is a flat rectangular metal plate with expansion coefficient α2, greater than α1. The length of the plate is L, measured up the slope of the roof. The component of the plate’s weight perpendicular to the roof is supported by a normal force uniformly distributed over the area of the plate. The coefficient of kinetic friction between the plate and the roof is μk. The plate is always at the same temperature as the roof, so we assume its temperature is continuously changing. Because of the difference in expansion coefficients, each bit of the plate is moving relative to the roof below it, except for points along a certain horizontal line running across the plate. We call this the stationary line. If the temperature is rising, parts of the plate below the stationary line are moving down relative to the roof and feel a force of kinetic friction acting up the roof. Elements of area above the stationary line are sliding up the roof and on them kinetic friction acts downward parallel to the roof. The stationary line occupies no area, so we assume no force of static friction acts on the plate while the temperature is changing. The plate as a whole is very nearly in equilibrium, so the net friction |
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| 55605 | A particular heat engine has a useful power output of 5.00 kW and an efficiency of 25.0%. The engine expels 8 000 J of exhaust energy in each cycle. Find
(a) The energy taken in during each cycle and
(b) The time interval for each cycle. |
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| 55606 | A particle starts from rest and accelerates as shown in Figure P2.12. Determine
(a) The particle’s speed at t = 10.0 s and at t = 20.0 s, and
(b) The distance traveled in the first 20.0 s. |
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| 55607 | A particle moves along the x axis according to the equation x = 2.00 + 3.00t - 1.00t 2, where x is in meters and t is in seconds. At t = 3.00 s, find
(a) The position of the particle,
(b) Its velocity, and
(c) Its acceleration. |
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| 55608 | A particle moves along the x axis. Its position is given by the equation x = 2 x 3t - 4t2 with x in meters and t in seconds. Determine
(a) Its position when it changes direction and
(b) Its velocity when it returns to the position it had at t = 0. |
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| 55609 | A particle moves according to the equation x = 10 t 2 where x is in meters and t is in seconds
(a) Find the average velocity for the time interval from 2.00 to 3.00 s.
(b) Find the average velocity for the time interval from 2.00 to 2.10 s. |
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| 55610 | A pair of eyeglass frames is made of epoxy plastic. At room temperature (20.0°C), the frames have circular lens holes 2.20 cm in radius. To what temperature must the frames be heated if lenses 2.21 cm in radius are to be inserted in them? The average coefficient of linear expansion for epoxy is 1.30 X 10-4 (°C)-1. |
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| 55611 | Oxygen at pressures much greater than 1 atm is toxic to lung cells. Assume that a deep-sea diver breathes a mixture of oxygen (O2) and helium (He). By weight, what ratio of helium to oxygen must be used if the diver is at an ocean depth of 50.0 m? |
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| 55612 | One of the most efficient heat engines ever built is a steam turbine in the Ohio valley, operating between 430°C and 1 870°C on energy from West Virginia coal to produce electricity for the Midwest.
(a) What is its maximum theoretical efficiency?
(b) The actual efficiency of the engine is 42.0%. How much useful power does the engine deliver if it takes in 1.40 X 105 J of energy each second from its hot reservoir? |
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| 55613 | One mole of oxygen gas is at a pressure of 6.00 atm and a temperature of 27.0°C. (a) If the gas is heated at constant volume until the pressure triples, what is the final temperature? (b) If the gas is heated until both the pressure and volume are doubled, what is the final temperature? |
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| 55614 | One mole of an ideal gas is heated slowly so that it goes from the PV state (Pi , Vi) to (3Pi, 3Vi) in such a way that the pressure is directly proportional to the volume.
(a) How much work is done on the gas in the process?
(b) How is the temperature of the gas related to its volume during this process |
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| 55615 | One mole of an ideal gas is contained in a cylinder with a movable piston. The initial pressure, volume, and temperature are Pi, Vi, and Ti, respectively. Find the work done on the gas for the following processes and show each process on a PV diagram: (a) An isobaric compression in which the final volume is half the initial volume. (b) An isothermal compression in which the final pressure is four times the initial pressure. (c) An is volumetric process in which the final pressure is three times the initial pressure |
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| 55616 | One mole of an ideal gas, initially at 300 K, is cooled at constant volume so that the final pressure is one fourth of the initial pressure. Then the gas expands at constant pressure until it reaches the initial temperature. Determine the work done on the gas. |
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| 55617 | One mole of an ideal gas does 3 000 J of work |
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| 55618 | One cubic meter of atomic hydrogen at 0°C and atmospheric pressure contains approximately 2.70 X 1025 atoms. The first excited state of the hydrogen atom has an energy of 10.2 eV above the lowest energy level, called the ground state. Use the Boltzmann factor to find the number of atoms in the first excited state at 0°C and at 10 000°C. |
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| 55619 | One container is filled with helium gas and another with argon gas. If both containers are at the same temperature, which molecules have the higher rms speed? Explain. |
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| 55620 | On the PV diagram for an ideal gas, one isothermal curve and one adiabatic curve pass through each point. Prove that the slope of the adiabat is steeper than the slope of the isotherm by the factor y. |
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| 55621 | On a Strange temperature scale, the freezing point of water is -15.0°S and the boiling point is + 60.0°S. Develop a linear conversion equation between this temperature scale and the Celsius scale. |
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| 55622 | On his honeymoon James Joule traveled from England to Switzerland. He attempted to verify his idea of the interconvertibility of mechanical energy and internal energy by measuring the increase in temperature of water that fell in a waterfall. If water at the top of an alpine waterfall has a temperature of 10.0°C and then falls 50.0 m (as at Niagara Falls), what maximum temperature at the bottom of the falls could Joule expect? He did not succeed in measuring the temperature change, partly because evaporation cooled the falling water, and also because his thermometer was not sufficiently sensitive. |
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