An engine releases 0.450 kJ of heat for every 0.100 kJ of work it does. What is the efficiency of the engine?
> During a Compton scattering experiment, an electron that was initially at rest recoils at 180° (i.e., in the direction of motion of the incident x-ray photon). If the recoil electron has a kinetic energy of 0.20 keV, what is the wavelength of the inciden
> An electron traveling horizontally from west to east enters a region where a uniform electric field is directed upward. What is the direction of the electric force exerted on the electron once it has entered the field?
> What are the magnitude and direction of the electric field midway between two point charges, −15 µC and +12 µC, that are 8.0 cm apart?
> A van de Graaff generator has a metal sphere of radius 15 cm. To what potential can it be charged before the electric field at its surface exceeds 3.0 × 106 N/C (which is sufficient to break down dry air and initiate a spark)?
> The St. Charles streetcar in New Orleans starts from rest and has a constant acceleration of 1.20 m/s2 for 12.0 s. (a) Draw a graph of vx versus t. (b) How far has the train traveled at the end of the 12.0 s? (c) What is the speed of the train at the
> Section 29.8 states that the total energy released by the proton-proton cycle is the same as that released by the carbon cycle CNO-I. Why must the total energy released be the same?
> An equilateral triangle has a point charge +q at each of the three vertices (A, B, C). Another point charge Q is placed at D, the midpoint of the side BC. Solve for Q if the total electric force on the charge at A due to the charges at B, C, and D is zer
> (a) Show that the ground-state energy of the hydrogen atom can be written E1 = −ke2/(2a0), where a0 is the Bohr radius. (b) Explain why, according to classical physics, an electron with energy E1 could never be found at a distance greater than 2a0 from
> Using the three point charges of Example 16.3, find the magnitude of the force on q1 due to the other two charges, q2 and q3. [Hint: After finding the force on q1 due to q2, separate that force into x- and y-components.]
> To test hearing at various frequencies, a resonant RLC circuit is connected to a speaker. The resonant frequency is selected by changing a variable capacitor. (a) For an RLC circuit with L = 300 mH, what is the necessary capacitance to achieve a resonan
> Harrison traveled 2.00 km west, then 5.00 km in a direction 53.0° south of west, then 1.00 km in a direction 60.0° north of west. (a) In what direction, and for how far, should Harrison travel to return to his starting point? (b) If Harrison returns di
> Two Styrofoam balls with the same mass m = 9.0 × 10−8 kg and the same positive charge Q are suspended from the same point by insulating threads of length L = 0.98 m. The separation of the balls is d = 0.020 m. What is the c
> A total charge of 7.50 × 10−6 C is distributed on two different small metal spheres. When the spheres are 6.00 cm apart, they each feel a repulsive force of 20.0 N. How much charge is on each sphere?
> In a DNA molecule, the base pair adenine and thymine is held together by two hydrogen bonds (see Fig. 16.5). Let’s model one of these hydrogen bonds as four point charges arranged along a straight line. Using the information in the figu
> A K+ ion and a Cl− ion are directly across from each other on opposite sides of a cell membrane 9.0 nm thick. What is the electric force on the K+ ion due to the Cl− ion? Ignore the presence of other charges.
> Two point charges are separated by a distance r and repel each other with forces of magnitude F. If their separation is reduced to 0.25 times the original value, what is the magnitude of the forces of repulsion?
> An arrangement of two pulleys, as shown in the figure, is used to lift a 48.0 kg crate a distance of 4.00 m above the starting point. Assume the pulleys and rope are ideal and that all rope sections are essentially vertical. (a) What is the change in the
> In the figure, a third point charge −q is placed at point P. What is the electric force on −q due to the other two point charges?
> A steel rule is calibrated for measuring lengths at 20.00°C. The rule is used to measure the length of a Vycor glass brick; when both are at 20.00°C, the brick is found to be 25.00 cm long. If the rule and the brick are both at 80.00°C, what would be the
> (a) What is the equivalent resistance between points A and B? Each resistor has the same resistance R. (b) What is the equivalent resistance between points B and C? (c) If a 32 V emf is connected to terminals A and B and if R = 2.0 Ω
> Prove Eq. (7-24) . [Hint: Start with , where is the net external force acting on a system and / is the total momentum of the system.]
> Magnetic forces cause an excess of positive ions to flow along one side of the artery and negative ions on the opposite side. What is the greatest possible potential difference across the artery?
> Two metal spheres separated by a distance much greater than either sphere’s radius have equal mass m and equal electric charge q. What is the ratio of charge to mass q/m in C/kg if the electrical and gravitational forces balance?
> A +2.0 nC point charge is 3.0 cm away from a −3.0 nC point charge. (a) What are the magnitude and direction of the 6electric force acting on the +2.0 nC charge? (b) What are the magnitude and direction of the electric force acting on the −3.0 nC charge?
> Electrons are accelerated through a potential difference of 8.95 kV and pass through a single slit of width 6.6 × 10−10 m. How wide is the central maximum on a screen that is 2.50 m from the slit?
> A bungee jumper leaps from a bridge and undergoes a series of oscillations. Assume g = 9.78 m/s2, (a) If a 60.0 kg jumper uses a bungee cord that has an unstretched length of 33.0 m and she jumps from a height of 50.0 m above a river, coming to rest jus
> In each of five situations, two point charges (Q1, Q2) are separated by a distance d. Rank them in order of the magnitude of the electric force on Q1, from largest to smallest. (a) Q1 = 1 µC, Q2 = 2 µC, d = 1 m (b) Q1 = 2 µC, Q2 = −1 uC, d = 1 m (c) Q1 =
> The figure shows PV diagrams for five systems as they undergo various thermodynamic processes. Rank them in order of the work done on the system, from greatest to least. Rank positive work higher than negative work.
> A contractor uses a paddle stirrer to mix a can of paint. The paddle turns at 28.0 rad/s and exerts a torque of 16.0 N·m on the paint, doing work on the paint at a rate power = τω = 16.0 N·m ×
> On a cold winter day, the outside temperature is −15.0°C. Inside the house the temperature is +20.0°C. Heat flows out of the house through a window at a rate of 220.0 W. At what rate is the entropy of the universe changing due to this heat conduction thr
> A train, traveling at a constant speed of 22 m/s, comes to an incline with a constant slope. While going up the incline, the train slows down with a constant acceleration of magnitude 1.4 m/s2. (a) Draw a graph of vx versus t where the x-axis points up
> A brick of mass 1.0 kg slides down an icy roof inclined at 30.0° with respect to the horizontal. (a) If the brick starts from rest, how fast is it moving when it reaches the edge of the roof 2.00 m away? Ignore friction. (b) Redo part (a) if the coeffi
> Electrical impedance tomography (EIT) is a medical imaging technique in which a low ac current is passed through part of the body. The impedance between the electrodes provides a measure of body composition. Consider a simplified model in which the body
> Two wooden crates with masses as shown are tied together by a horizontal cord. Another cord is tied to the first crate, and it is pulled with a force of 195 N at an angle of 20°, as shown. Each crate has a coefficient of kinetic friction of 0.
> What is the change in entropy of 10 g of steam at 100°C as it condenses to liquid water at 100°C?
> A pot containing 2.00 kg of water is sitting on a hot stove, and the water is stirred violently by a mixer that does 6.0 kJ of mechanical work on the water. The temperature of the water rises by 4.00°C. What quantity of heat flowed into the water from th
> How much does the internal energy change for 1.00 m3 of water after it has fallen from the top of a waterfall and landed in the river 11.0 m below? Assume no heat flow from the water to the air.
> Verify the units in Eq. (15-5)—that is, show that the SI unit of pressure times volume is equal to the SI unit of work.
> About 5.0 × 104 m above Earth's surface, the atmosphere is sufficiently ionized that it behaves as a conductor. Earth and the ionosphere form a giant spherical capacitor, with the lower atmosphere acting as a leaky dielectric. (a) Find the capacitance C
> A heat engine takes in 125 kJ of heat from a reservoir at 815 K and exhausts 82 kJ to a reservoir at 293 K. (a) What is the efficiency of the engine? (b) What is the efficiency of an ideal engine operating between the same two reservoirs?
> Neutron diffraction by a crystal can be used to make a velocity selector for neutrons. Suppose the spacing between the relevant planes in the crystal is d = 0.20 nm. A beam of neutrons is incident making an angle θ = 10.0° with respect to the planes. The
> An ideal engine has an efficiency of 0.725 and uses gas from a hot reservoir at a temperature of 622 K. What is the temperature of the cold reservoir to which it exhausts heat?
> A 2.0 kg block is released from rest and allowed to slide down a frictionless surface and into a spring. The far end of the spring is attached to a wall, as shown. The initial height of the block is 0.50 m above the lowest part of the slide and the sprin
> A star near the visible edge of a galaxy travels in a uniform circular orbit. It is 40 000 ly (light-years) from the galactic center and has a speed of 275 km/s. (a) Estimate the total mass of the galaxy based on the motion of the star. [Hint: For this
> A steam engine has a piston with a diameter of 15.0 cm and a stroke (the displacement of the piston) of 20.0 cm. The average pressure applied to this piston is 1.3 × 105 Pa. What operating frequency in cycles per second (Hz) would yield an average power
> An air conditioner whose coefficient of performance is 2.00 removes 1.73 × 108 J of heat from a room per day. How much does it cost to run the air conditioning unit per day if electricity costs $0.10 per kilowatt-hour? (Note that 1 kilowatt-hour = 3.6 ×
> A house with its own well has a pump in the basement with an output pipe of inner radius 6.3 mm. The pump can maintain a gauge pressure of 410 kPa in the output pipe. A showerhead on the second floor (6.7 m above the pump’s output pipe) has 36 holes, eac
> Emil is tossing an orange of mass 0.30 kg into the air. (a) Emil throws the orange straight up and then catches it, throwing and catching it at the same point in space. What is the change in the potential energy of the orange during its trajectory? Igno
> How much heat does a heat pump with a coefficient of performance of 3.0 deliver when supplied with 1.00 kJ of electricity?
> The intensity (power per unit area) of the sunlight incident on Earth's surface, averaged over a 24 h period, is about 0.20 kW/m2. If a solar power plant is to be built with an output capacity of 1.0 × 109 W, how big must the area of the solar energy col
> The United States generates about 5.0 × 1016 J of electric energy a day. This energy is equivalent to work, since it can be converted into work with almost 100% efficiency by an electric motor. (a) If this energy is generated by power plants with an ave
> A heat pump delivers heat at a rate of 7.81 kW for 10.0 h. If its coefficient of performance is 6.85, how much heat is taken from the cold reservoir during that time?
> What is the efficiency of an electric generator that produces 1.17 kW·h per kilogram of coal burned? The heat of combustion of coal is 6.71 × 106 J/kg.
> Using the stress-strain graph for bone (Fig. 10.4c), calculate Young’s moduli for tension and for compression. Consider only small stresses.
> A surgeon is attempting to correct a detached retina by using a pulsed laser. (a) If the pulses last for 20.0 ms and if the output power of the laser is 0.500 W, how much energy is in each pulse? (b) If the wavelength of the laser light is 643 nm, how
> An object located at the origin and having mass M explodes into three pieces having masses M/4, M/3, and 5M/12. The pieces scatter on a horizontal frictionless xy-plane. The piece with mass M/4 flies away with velocity 5.0 m/s at 37° above the x-axis. Th
> Repeat Problem 51(a), this time assuming the electron is ultra- relativistic (E ≈ pc). Is the assumption justified?
> A heat engine follows the cycle shown in the figure. (a) How much net work is done by the engine in one cycle? (b) What is the net heat flow into the engine per cycle?
> If an electron moves from one point at a potential of −100.0 V to another point at a potential of +100.0 V, how much work is done by the electric field?
> (a) Which might describe a heat engine? (b) Which might describe a heat pump? (c) Which might describe a refrigerator? Explain.
> An airline executive decides to economize by reducing the amount of fuel required for long-distance flights. He orders the ground crew to remove the paint from the outer surface of each plane. The paint removed from a single plane has a mass of approxima
> Rank the processes in order of the net work done by the system per cycle, from greatest to least. Rank positive work done by the system (as in an engine) higher than negative work done by the system (as in a heat pump).
> Suppose 1.00 mol of oxygen is heated at constant pressure of 1.00 atm from 10.0°C to 25.0°C. (a) How much heat is absorbed by the gas? (b) Using the ideal gas law, calculate the change of volume of the gas in this process. (c) What is the work done by
> An ideal gas is in contact with a heat reservoir so that it remains at a constant temperature of 300.0 K. The gas is compressed from a volume of 24.0 L to a volume of 14.0 L. During the process, the mechanical device pushing the piston to compress the ga
> A transverse wave on a string is described by where A = 0.40 mm, ω = 39.27 rad/s, and k = 6.0 rad/m. Draw a motion diagram for the point x = 0 for the times t = 0, 0.010 s, 0, 0.020 s, 0.030 s, and 0.040 s.
> If the pressure on a fish increases from 1.1 atm to 1.2 atm, its swim bladder decreases in volume from 8.16 mL to 7.48 mL while the temperature of the air inside remains constant. How much work is done on the air in the bladder?
> On a graph of ax versus time, what quantity does the area under the graph represent?
> An ideal gas is heated at a constant pressure of 2.0 × 105 Pa from a temperature of −73°C to a temperature of +27°C. The initial volume of the gas is 0.10 m3. The heat energy supplied to the gas in this process is 25 kJ. What is the increase in internal
> A balloon contains 200.0 L of nitrogen gas at 20.0°C and at atmospheric pressure. How much energy must be added to raise the temperature of the nitrogen to 40.0°C while allowing the balloon to expand at atmospheric pressure?
> In a refrigerator, 2.00 mol of an ideal monatomic gas are taken through the cycle shown in the figure. The temperature at point A is 800.0 K. (a) What are the temperature and pressure at point D? (b) What is the net work done on the gas as it is taken
> The three processes shown with Multiple Choice Question 8 involve a diatomic ideal gas. Rank them in order of the change in internal energy, from greatest to smallest.
> (a) Find the equivalent resistance between points A and B for the combination of resistors shown. (b) An 18 V emf is connected to the terminals A and B. What is the current through the 1.0 Ω resistor connected directly to point A? (
> The beam emerging from a ruby laser passes through a circular aperture 5.0 mm in diameter. (a) If the spread of the beam is limited only by diffraction, what is the angular spread of the beam? (b) If the beam is aimed at the Moon, how large a spot would
> Copper and aluminum are being considered for the cables in a high- voltage transmission line where each must carry a current of 50 A. The resistance of each cable is to be 0.15 Ω per kilometer. (a) If this line carries power from Niagara Falls to New Yo
> Brad tries out a weight-loss plan that involves repeatedly lifting a 50.0 kg barbell from the floor over his head to a height of 2.0 m. If he is able to complete three such lifts per minute, how long will it take for him to lose 0.50 kg of fat? “Burning”
> Some forms of cancer can be treated using proton therapy in which proton beams are accelerated to high energies, then directed to collide into a tumor, killing the malignant cells. Suppose a proton accelerator is 4.0 m long and must accelerate protons fr
> Find the work done by gravity on the sliding crate.
> An ideal monatomic gas is taken through the cycle in the PV diagram. (a) If there are 0.0200 mol of this gas, what are the temperature and pressure at point C? (b) What is the change in internal energy of the gas as it is taken from A to B? (c) How muc
> On a graph of vx versus time, what quantity does the slope of the graph represent?
> On a cold day, Ming rubs her hands together to warm them up. She presses her hands together with a force of 5.0 N. Each time she rubs them back and forth, they move a distance of 16 cm with a coefficient of kinetic friction of 0.45. Assuming no heat flow
> During basketball practice Shane made a jump shot, releasing a 0.60 kg basketball from his hands at a height of 2.0 m above the floor with a speed of 7.6 m/s. The ball swooshes through the net at a height of 3.0 m above the floor and with a speed of 4.5
> A 64 kg sky diver jumped out of an airplane at an altitude of 0.90 km. She opened her parachute after a while and eventually landed on the ground with a speed of 5.8 m/s. How much energy was dissipated by air resistance during the jump?
> A child of mass 15 kg climbs to the top of a slide that is 1.7 m above a horizontal run that extends for 0.50 m at the base of the slide. After sliding down, the child comes to rest just before reaching the very end of the horizontal portion of the slide
> In a physics lab, a student accidentally drops a 25.0 g brass washer into an open dewar of liquid nitrogen at 77.2 K. How much liquid nitrogen boils away as the washer cools from 293 K to 77.2 K? The latent heat of vaporization for nitrogen is 199.1 kJ/k
> Charges of −12.0 nC and −22.0 nC are separated by 0.700 m. What is the potential midway between the two charges?
> What is the maximum possible torque on the molecule due to the electric field?
> In an RLC series circuit, these three elements are connected in series: a resistor of 60.0 Ω, a 40.0 mH inductor, and a 0.0500 F capacitor. The series elements are connected across the terminals of an ac oscillator with an rms voltage of 10.0 V. Find the
> In an emergency, it is sometimes the practice of medical professionals to immerse a patient who suffers from heat stroke in an ice bath, a mixture of ice and water in equilibrium at 0°C, in order to reduce her body temperature. (a) If a 75 kg patient wh
> As heat flows into a substance, its temperature changes according to the graph in the diagram. For which sections of the graph is the substance undergoing a phase change? For the sections you identified, what kind of phase change is occurring?
> A chamber with a fixed volume of 1.0 m3 contains a monatomic gas at 3.00 × 102 K. The chamber is heated to a temperature of 4.00 × 102 K. This operation requires 10.0 J of heat. (Assume all the energy is transferred to the gas.) How many gas molecules ar
> A 200.0 µF capacitor is placed across a 12.0 V battery. When a switch is thrown, the battery is removed from the capacitor and the capacitor is connected across a heater that is immersed in 1.00 cm3 of water. Assuming that all the energy from the capacit
> What is the de Broglie wavelength of an electron with kinetic energy 7.0 TeV?
> (a) What would the net charges on the Sun and Earth have to be if the electric force instead of the gravitational force were responsible for keeping Earth in its orbit? There are many possible answers, so restrict yourself to the case where the magnitude
> Jill takes in 0.021 mol of air in a single breath. The air is taken in at 20°C and exhaled at 35°C. (a) How much heat leaves her body in a single breath due to the temperature increase of the air? Ignore the humidification of the air in the lungs and tre
> Consider two falling objects. Their masses are 3.0 kg and 4.0 kg. At time t = 0, the two are released from rest. What is the velocity of their CM at t = 10.0 s? Ignore air resistance.
> A muon decay is described by . What is the maximum kinetic energy of the electron, if the muon was at rest? Assume that the electron is extremely relativistic and ignore the small masses of the neutrinos.
> Imagine that 501 people are present in a movie theater of volume 8.00 × 103 m3 that is sealed shut so no air can escape. Each person gives off heat at an average rate of 110 W. By how much will the temperature of the air have increased during a 2.0 h mov
> A Foucault pendulum has an object with a mass of 15.0 kg hung by a thin 14.0 m wire. (a) What is the oscillation frequency of this pendulum? (b) If the pendulum has a maximum oscillation angle of 6.10°, what is the maximum speed of this pendulum? (c)
> A heating coil inside an electric kettle delivers 2.1 kW of electric power to the water in the kettle. How long will it take to raise the temperature of 0.50 kg of water from 20.0°C to 100.0°C?
> A 24 V emf is connected to terminals A and B in the following circuit. Find the current in each of the resistors.
