An electric space heater dissipates 1320 W of power via electromagnetic radiation and convection when connected to 120 V. When current is unknown, power can be expressed as P = V 2 /R . Use this...
A friend says that sound travels faster in warm air than in cooler air. Do you agree or disagree?
Physics instructor Peter Hopkinson delights in bringing physics into social situations. When dining out with friends, he produces resonance in an empty wine glass by rubbing his wetted fingers on its...
Quantum mechanics is one of the most daunting of all areas in physics. To students encountering this subject for the first time at the introductory level, quantum mechanics can seem mysterious, even...
How much unpolarized light does an ideal Polaroid filter transmit?
Which electrons are most responsible for the properties of an atom?
How might you distinguish a sodium-vapor streetlight from a mercury-vapor streetlight?
If matter is made of atoms, and atoms are made of subatomic particles, what comes together to create subatomic particles? Where might you find such information?
Why is the rusting of iron considered to be a chemical change?
Which element within a compound is given first in the compounds name?
A driver states that she was doing 80 when stopped by the police. Is that a clear statement? Would this be interpreted differently in England than it would be in the United States? Explain.
In shooting a free throw in basketball, what is the primary advantage that a high, arching shot has over one with a flatter trajectory? Explain.
A 4-kg block is acted upon by three horizontal forces as shown in the diagram. a. What is the net horizontal force acting on the block? b. What is the horizontal acceleration of the block? 10 N 5 N...
At a given instant in time, a 4-kg rock that has been dropped from a high cliff experiences a force of air resistance of 15 N. What are the magnitude and direction of the acceleration of the rock?...
At a given instant in time, a 5-kg rock is observed to be falling with an acceleration of 7.0 m/s 2 . What is the magnitude of the force of air resistance acting upon the rock at this instant?
A 0.5-kg book rests on a table. A downward force of 6 N is exerted on the top of the book by a hand pushing down on the book. a. What is the magnitude of the gravitational force acting upon the book?...
Assume that a passenger in a rollover accident must turn through a radius of 3.0 m to remain in the seat of the vehicle. Assume also that the vehicle makes a complete turn in 1 second. a. Using the...
Suppose that the physics instructor pictured in figure 6.15 gives the bowling ball a push as she releases it. Will the ball return to the same point or will her chin be in danger? Explain.
A force of 50 N is used to drag a crate 4 m across a floor. The force is directed at an angle upward from the crate so that the vertical component of the force is 30 N and the horizontal component is...
What kind of weather does a continental tropical air mass bring?
An underground mass of salt may form a dome trapping a petroleum reservoir. Compute the gravitational anomaly (deviation of gravitational acceleration) produced by an underground salt mass, where for...
Compare the energy density of oil and geothermal fluid at 250 C pumped from oil/geothermal wells at a rate of 30 L/s. To make a fair comparison, assume that the oil is transformed into useful...
According to the US EIA, 1350 Mt(CO 2 ) were emitted from combustion of coal and 530 Mt(CO 2 ) we re emitted from combustion of natural gas for electricity production in 2015. Using the data in...
Confirm explicitly that the work (37.2) done in isothermal compression of a CAES system with volume V, and low, high, and ambient atmospheric pressures p L , p H , p 0 is equivalent to the energy...
In a lithium-iodine (LiI) battery, a solid lithium anode is surrounded by a polymer impregnated with iodine. The net reaction, Li + I 2 LiI, has a standard reaction free energy of G 0 = 266.9 kJ/mol...
Verify the computations in Example 37.2 describing the McIntosh CAES plant. In particular, use eq. (37.2) to compute the energy stored through isothermal compression; verify that 1.4 TJ of work would...
A load consists of a large number N of identical resistors R (e.g. incandescent lights, toasters,. . . ) in parallel.Suppose they are powered by an AC generator with RMS voltage V. Compare the line...
Compute the time for the oceanic mixed layer (350 Mkm 2 200 m) to warm by 3.2 K, using 50% of the energy coming from a change in radiative forcing of 3.7 W/m 2 . Advanced version: assume that...
Estimate the contribution to global sea level rise over a century if Greenlands glaciers continue to melt at a rate of 290 Gt/y.
In 13.3.5 we specified a realistic Rankine cycle working between T + = 600 C and T = 36 C. We found its efficiency to be 38%.What is its 2nd law efficiency?
A three-phase generator delivers voltages V A (t) = V 0 cost, V B (t) = V 0 cos(t + 2/3), and V C (t) = V 0 cos (t 2/3). First, assume that all three phases are connected to identical, purely...
Fluorescent light bulbs have significant impedance. Measurements on a compact fluorescent bulb with luminosity equivalent to a 40 W incandescent indicate that it consumes 9 W real power. Measurements...
Based upon the descriptions provided in table 1.2, which subfields of physics are involved in explaining why an ice cube melts? Which subfields are involved in explaining how an airplane flies?...
A uniform metal wire is bent into the shape of an L. Will the center of gravity for the wire lie on the wire itself? Explain.
The rotational velocity of a spinning disk decreases from 6 rev/s to 3 rev/s in a time of 12 s. What is the rotational acceleration of the disk?
A torque of 60 Nm producing a counterclockwise rotation is applied to a wheel about its axle. A frictional torque of 10 Nm acts at the axle. a. What is the net torque about the axle of the wheel? b....
Two 0.2-kg masses are located at either end of a 1-m long, very light and rigid rod as in the diagram. What is the rotational inertia of this system about an axis through the center of the rod? Axis...
Is it possible for a 100-lb woman to exert a greater pressure on the ground than a 250-lb man? Explain.
The same force is applied to two cylinders that contain air. One has a piston with a large area, and the other has a piston with a small area. In which cylinder will the pressure be greater? Explain
A 4-m long plank with a weight of 80 N is placed on a dock with 1 m of its length extended over the water, as in the diagram. The plank is uniform in density so that the center of gravity of the...
Why are bicycle tires often inflated to a higher pressure than automobile tires, even though the automobile tires must support a much larger weight? Explain.
The fluid in a hydraulic system pushes against two pistons, one with a large area and the other with a small area. a. Which piston experiences the greater force due to fluid pressure acting on it?...
If the output piston in a hydraulic pump exerts a greater force than one applied to the input piston, is the pressure at the output piston also larger than at the input piston? Explain.
When a mercury barometer is used to measure atmospheric pressure, does the closed end of the tube above the mercury column usually contain air? Explain.
Could we use water instead of mercury to make a barometer? What advantages and disadvantages would be associated with the use of water? Explain.
If you climbed a mountain carrying a mercury barometer, would the level of the mercury column in the glass tube of the barometer increase or decrease (compared to the mercury reservoir) as you climb...
If an object has a smaller density than water, will the object stay fully submerged, partly submerged, or rise completely out of the water when it is released underwater? Explain.
A 250-lb man supports all of his weight on a show shoe with an area of 200 in 2 . What pressure is exerted on the snow (in pounds per square inch)?
The pressure of a gas contained in a cylinder with a movable piston is 450 Pa (450 N/m 2 ). The area of the piston is 0.2 m2. What is the magnitude of the force exerted on the piston by the gas?
In a hydraulic system, a force of 400 N is exerted on a piston with an area of 0.001m 2 . The load-bearing piston in the system has an area of 0.2m 2 . a. What is the pressure in the hydraulic fluid?...
The load-bearing piston in a certain hydraulic system has an area 50 times as large as the input piston. If the larger piston supports a load of 6000 N, how large a force must be applied to the input...
A block of wood of uniform density floats so that exactly half of its volume is underwater. The density of water is 1000 kg/m 3 . What is the density of the block?
A certain boat displaces a volume of 4.5 m 3 of water. (The density of water is 1000 kg/m 3 .) a. What is the mass of the water displaced by the boat? b. What is the buoyant force acting on the boat?
Water emerges from a faucet at a speed of 1.5 m/s. After falling a short distance, its speed increases to 3 m/s as a result of the gravitational acceleration. By what number would you multiply the...
Water has a density of 1000 kg/m 3 . The depth of a swimming pool at the deep end is about 3 m. a. What is the volume of a column of water 3 m deep and 0.5m 2 in cross-sectional area? b. What is the...
An object has a temperature of 45C. What is its temperature in degrees Fahrenheit?
The temperature on a winter day is 14F. What is the temperature in degrees Celsius?
The temperature in a residence-hall room is 24C. What is the temperature of the room on the absolute (Kelvin) temperature scale?
The temperature on a warm summer day is 95F. What is this temperature a. In degrees Celsius? b. On the absolute (Kelvin) scale?
The temperature of a beaker of water is 318.2 K. What is this temperature a. In degrees Celsius? b. In degrees Fahrenheit?
How much heat is required to raise the temperature of 70 g of water from 20C to 80C?
How much heat must be removed from a 200-g block of copper to lower its temperature from 150C to 30C? The specific heat capacity of copper is 0.093 cal/gC.
How much heat must be added to 60 g of ice at 0C to melt the ice completely?
How much heat must be added to 120 g of water at an initial temperature of 60C to a. Heat it to the boiling point? b. Completely convert the 100C water to steam?
While a gas does 300 J of work on its surroundings, 800 J of heat is added to the gas. What is the change in the internal energy of the gas?
The volume of an ideal gas is increased from 0.8 m 3 to 2.4 m 3 while maintaining a constant pressure of 1000 Pa (1 Pa 1 N/m 2 ). How much work is done by the gas in this expansion?
If the initial temperature in exercise E14 is 700K, what is the final temperature? Data from Problem 14 The volume of an ideal gas is increased from 0.8 m 3 to 2.4 m 3 while maintaining a constant...
Heat is added to an object initially at 30C, increasing its temperature to 80C. a. What is the temperature change of the object in Fahrenheit degrees? b. What is the temperature change of the object...
A heat engine with an efficiency of 25% does 400 J of work in each cycle. How much heat must be supplied from the high-temperature source in each cycle?
In one cycle, a heat engine takes in 900 J of heat from a high-temperature reservoir and releases 600 J of heat to a lower-temperature reservoir. a. How much work is done by the engine in each cycle?...
A heat engine with an efficiency of 40% takes in 600 J of heat from the high-temperature reservoir in each cycle. a. How much work does the engine do in each cycle? b. How much heat is released to...
In one cycle, a heat engine does 400 J of work and releases 500 J of heat to a lower-temperature reservoir. a. How much heat does it take in from the higher temperature reservoir? b. What is the...
When two different materials are rubbed together, do the two materials acquire the same type of charge or different types of charge? Explain how you could justify your answer with a simple experiment.
Two pith balls are both charged by contact with a plastic rod that has been rubbed by cat fur. a. What sign will the charges on the pith balls have? Explain. b. Will the two pith balls attract or...
When a glass rod is rubbed by a nylon cloth, which of these two objects gains electrons? Explain.
Two pith balls are charged by touching one to a glass rod that has been rubbed with a nylon cloth and the other to the cloth itself. a. What sign will the charge on each pith ball have? Explain. b....
Do the two metal-foil leaves of an electroscope gain charges of opposite sign when the electroscope is charged? Explain.
If you charge an electroscope with a plastic rod that has been rubbed with cat fur, will the metal leaves of the electroscope move farther apart or come closer together when you bring the cat fur...
When you comb your hair with a plastic comb, what will the sign be on the charge acquired by the comb? Explain. (Compare this process to rubbing a plastic rod with cat fur.)
Describe how Benjamin Franklins single-fluid model can explain what happens when we charge a glass rod by rubbing it with a nylon cloth. How do we get two types of charge from a single fluid? Explain.
If you touch the metal ball of a charged electroscope with an uncharged glass rod held in your hand, will the electroscope discharge completely? Explain.
If you touch the ball of a charged electroscope with your finger, will it discharge? What does this suggest about the conducting properties of people? Explain.
Consider the circuit shown, where the wires are connected to either side of a wooden block as well as to the light bulb. Will the bulb light in this arrangement? Explain. 1.5 V Wood block Q5 Diagram
Suppose that one of the two charges in synthesis problem 2 is twice as large as the other one. Use the procedures suggested in parts a and b of synthesis problem 2 for this new situation. (When...
Suppose that four equal positive charges are located at the corners of a square, as in the diagram. a. Using small arrows, indicate the direction of the electric field at each of the labeled points....
Consider the circuit shown. Could we increase the brightness of the bulb by connecting a wire between points A and B? Explain. A B Q6 Diagram
Two circuit diagrams are shown. Which one, if either, will cause the light bulb to light? Explain your analysis of each case. 1.5 V (a) Q7 Diagram 1.5 V (b) Open switch
Suppose that we use an uncoated metal clamp to hold the wires in place in the battery-and-bulb circuit shown. Will this be effective in keeping the bulb burning brightly? Explain. 1.5 V Q8 Diagram
Two resistors are connected in series with a battery as shown in the diagram. R 1 is less than R 2 . a. Which of the two resistors, if either, has the greater current flowing through it? Explain. b....
How does a bimetallic strip break a circuit when things heat up? Explain.
A charge of 30 C passes at a steady rate through a resistor in a time of 5s. What is the current through the resistor?
A current of 2.5 A flows through a battery for 1 min. How much charge passes through the battery in that time?
A 24- resistor in a circuit has a voltage difference of 6 V across its leads. What is the current through this resistor?
A current of 1.5 A is flowing through a resistance of 18 . What is the voltage difference across this resistance?
A current of 0.6 A flows through a resistor with a voltage difference of 120 V across it. What is the resistance of this resistor?
Three 20- resistors are connected in series to a 6-V battery of negligible internal resistance. a. What is the current flowing through each resistor? b. What is the voltage difference across each...
A 40- resistor and a 60- resistor are connected in series to a 12-V battery. a. What is the current flowing through each resistor? b. What is the voltage difference across each resistor?
Two resistors, each having a resistance of 8 , are connected in parallel. What is the equivalent resistance of this combination?
Three resistors of 3 , 6 , and 2 are connected in parallel with one another. What is the equivalent resistance of this combination?
A 9-V battery in a simple circuit produces a current of 1.5 A through the circuit. How much power is being delivered by the battery?