A cooking oven has a top surface temperature of 45C when exposed to still air. At this condition the inside oven temperature and room air temperature are 180C and 20C, respectively, and heat is...
A 1-in., 16-BWG copper tube, 10ft long, has its outside surface maintained at 240F. Air at 60F and atmospheric pressure is forced past this tube with a velocity of 40 fps. Determine the heat flux...
Two thousand watts of electrical energy are to be dissipated through copper plates measuring 5 cm by 10 cm by 0.6 cm immersed in water at 390 K. How many plates would you recommend? Substantiate all...
A vertical flat surface 2 ft high is maintained at 60F. If saturated ammonia at 85F is adjacent to the surface, what heat- transfer coefficient will apply to the condensation process? What total heat...
Water at 50F is available for cooling at a rate of 400 Ib m /h. It enters a double-pipe heat exchanger with a total area of 18 ft 2 . Oil, with c p = 0.45 Btu/1b m , F, enters the exchanger at 250F....
The distribution of solar energy incident on Earth can be approximated as being from a black body at 5800 K. Two kinds of glass, plain and tinted, are being considered for use in windows. The...
Derive equation (25-11) for component A in terms of molar units, starting with the control-volume expression for the conservation of mass. CA - RA = 0 V NA +: (25-11)
a. Find an expression for the capacitance of a spherical capacitor, consisting of concentric spherical shells of radii R 1 (inner shell) and R 2 (outer shell). b. A spherical capacitor with a 1.0 mm...
You are given the equation(s) used to solve a problem. For each of these, you are to a. Write a realistic problem for which this is the correct equation(s). b. Finish the solution of the problem. +...
A vacuum-insulated parallel-plate capacitor with plate separation d has capacitance C 0 . What is the capacitance if an insulator with dielectric constant k and thickness d/2 is slipped between the...
Estimate the value of the gas-phase diffusion coefficient for the following gas pairs using the Hirschfelder equation: a. Carbon dioxide and air at 310 K and 1:5 10 5 Pa b. Ethanol and air at 325 K...
The label rubbed off one of the capacitors you are using to build a circuit. To find out its capacitance, you place it in series with a 10 F capacitor and connect them to a 9.0 V battery. Using your...
An isolated 5.0 F parallel-plate capacitor has 4.0 mC of charge. An external force changes the distance between the electrodes until the capacitance is 2.0 F. How much work is done by the external...
Capacitors C 1 = 10 F and C 2 = 20 F are each charged to 10 V, then disconnected from the battery without changing the charge on the capacitor plates. The two capacitors are then connected in...
Six identical capacitors with capacitance C are connected as shown in FIGURE P26.60. a. What is the equivalent capacitance of these six capacitors? b. What is the potential difference between points...
A hemispherical droplet of liquid water, lying on a flat surface, evaporates by molecular diffusion through still air surrounding the droplet. The droplet initially has a radius R. As the liquid...
The electric potential is 40 V at point A near a uniformly charged sphere. At point B, 2.0 m farther away from the sphere, the potential has decreased by 0.16 mV. How far is point A from the center...
Metal sphere 1 has a positive charge of 6.0 nC. Metal sphere 2, which is twice the diameter of sphere 1, is initially uncharged. The spheres are then connected together by a long, thin metal wire....
Suppose a time machine has just brought you forward from 1750 (post-Newton but pre-electricity) and youve been shown the lightbulb demonstration of Figure Q27.1. Do observations or simple...
The 90 F capacitor in a defibrillator unit supplies an average of 6500 W of power to the chest of the patient during a discharge lasting 5.0 ms. To what voltage is the capacitor charged?
50 pJ of energy is stored in a 2.0 cm 2.0 cm 2.0 cm region of uniform electric field. What is the electric field strength?
You need a capacitance of 50 F, but you dont happen to have a 50 F capacitor. You do have a 75 F capacitor. What additional capacitor do you need to produce a total capacitance of 50 F? Should you...
What is the equivalent capacitance of the three capacitors in Figure EX26.28? 20 F 13 F 30 F FIGURE EX26.28
A spherical ball of solid, nonporous naphthalene, a mothball, is suspended in still air. The naphthalene ball slowly sublimes, releasing the naphthalene vapor into the surrounding air by molecular...
A 150 g particle at x = 0 is moving at 2.00 m/s in the +x-direction. As it moves, it experiences a force given by F x = (0.250 N) sin (x/2.00 m). What is the particles speed when it reaches x = 3.14...
A horizontal spring with spring constant 750 N/m is attached to a wall. An athlete presses against the free end of the spring, compressing it 5.0 cm. How hard is the athlete pushing?
A 35-cm-long vertical spring has one end fixed on the floor. Placing a 2.2 kg physics textbook on the spring compresses it to a length of 29 cm. What is the spring constant?
A horizontal spring with spring constant 85 N/m extends outward from a wall just above floor level. A 1.5 kg box sliding across a frictionless floor hits the end of the spring and compresses it 6.5...
One mole (6.02 10 23 atoms) of helium atoms in the gas phase has 3700 J of microscopic kinetic energy at room temperature. If we assume that all atoms move with the same speed, what is that speed?...
A baggage handler throws a 15 kg suitcase along the floor of an airplane luggage compartment with a speed of 1.2 m/s. The suitcase slides 2.0 m before stopping. Use work and energy to find the...
At midday, solar energy strikes the earth with an intensity of about 1 kW/m 2 . What is the area of a solar collector that could collect 150 MJ of energy in 1 h? This is roughly the energy content of...
A 50 kg sprinter, starting from rest, runs 50 m in 7.0 s at constant acceleration. a. What is the magnitude of the horizontal force acting on the sprinter? b. What is the sprinters power output at...
A 70 kg human sprinter can accelerate from rest to 10 m/s in 3.0 s. During the same time interval, a 30 kg greyhound can go from rest to 20 m/s. What is the average power output of each? Average...
A 1000 kg elevator accelerates upward at 1.0 m/s 2 for 10 m, starting from rest. a. How much work does gravity do on the elevator? b. How much work does the tension in the elevator cable do on the...
Susans 10 kg baby brother Paul sits on a mat. Susan pulls the mat across the floor using a rope that is angled 30 above the floor. The tension is a constant 30 N and the coefficient of friction is...
A particle of mass m moving along the x-axis has velocity v x = v 0 sin (x/2L). How much work is done on the particle as it moves (a) From x = 0 to x = L (b) From x = 0 to x = 2L?
A ball shot straight up with kinetic energy K 0 reaches height h. What height will it reach if the initial kinetic energy is doubled?
A pile driver lifts a 250 kg weight and then lets it fall onto the end of a steel pipe that needs to be driven into the ground. A fall of 1.5 m drives the pipe in 35 cm. What is the average force...
Recall from example 3, Chapter 25, that the differential model for the radial concentration profile of dissolved oxygen within one cylindrical engineered tissue bundle (Figure 25.8) is with boundary...
A 50 kg ice skater is gliding along the ice, heading due north at 4.0 m/s. The ice has a small coefficient of static friction, to prevent the skater from slipping sideways, but k = 0. Suddenly, a...
Youre fishing from a tall pier and have just caught a 1.5 kg fish. As it breaks the surface, essentially at rest, the tension in the vertical fishing line is 16 N. Use work and energy to find the...
Hookes law describes an ideal spring. Many real springs are better described by the restoring force (F Sp ) s = -ks - q(s) 3 , where q is a constant. Consider a spring with k = 250 N/m and q = 800...
The force acting on a particle is F x = F 0 e-x/L . How much work does this force do as the particle moves along the x-axis from x = 0 to x = L?
An electric dipole consists of two equal but opposite electric charges, +q and -q, separated by a small distance d. If another charge Q is distance x from the center of the dipole, in the plane...
Hydrogen embrittlement weakens the mechanical strength of cast iron. This phenomenon frequently occurs in cast-iron pressure vessels containing hydrogen (H 2 ) gas. The H 2 gas dissolves into the...
When a 65 kg cheerleader stands on a vertical spring, the spring compresses by 5.5 cm. When a second cheerleader stands on the shoulders of the first, the spring compresses an additional 4.5 cm. What...
Two identical horizontal springs are attached to opposite sides of a box that sits on a frictionless table. The outer ends of the springs are clamped while the springs are at their equilibrium...
A spring of equilibrium length L 1 and spring constant k 1 hangs from the ceiling. Mass m 1 is suspended from its lower end. Then a second spring, with equilibrium length L 2 and spring constant k 2...
A horizontal spring with spring constant 250 N/m is compressed by 12 cm and then used to launch a 250 g box across the floor. The coefficient of kinetic friction between the box and the floor is...
A simple experiment is set up to measure the effective diffusion coefficient of blue dextran dye into a rigid agarose gel. An aqueous, well-mixed solution of liquid height 10 cm con taining 1.0 g/L...
The contamination of water-saturated soils with toxic organic solvents is an important environmental problem. The organic solvents can dissolve into to the water and diffuse through the...
A 90 kg firefighter needs to climb the stairs of a 20-m-tall building while carrying a 40 kg backpack filled with gear. How much power does he need to reach the top in 55 s?
A hydroelectric power plant uses spinning turbines to transform the kinetic energy of moving water into electric energy with 80% efficiency. That is, 80% of the kinetic energy becomes electric...
Consider the porous slab shown in the figure below. Very tiny pores of 20 A diameter run through the 2.0 cm slab in parallel array. This device will ultimately serve as a drug delivery vehicle for a...
The block of mass M in FIGURE P7.36 slides on a frictionless surface. Find an expression for the tension in the string. Massless string Massless, fric- tionless pulley FIGURE P7.36
A farmer uses a tractor to pull a 150 kg bale of hay up a 15 incline to the barn at a steady 5.0 km/h. The coefficient of kinetic friction between the bale and the ramp is 0.45. What is the tractors...
A Porsche 944 Turbo has a rated engine power of 217 hp. 30% of the power is lost in the drive train, and 70% reaches the wheels. The total mass of the car and driver is 1480 kg, and two-thirds of the...
Jasmone (molecular formula C 11 H 16 O) is a valuable specialty chemical that is obtained from the jasmine plant. A common method of manufacture is to extract the plant material in water, and then...
One step in the processing of cucumbers to pickles is the pickling process itself. In one method of making pickles, young cucumbers with no waxy skins are soaked in a NaC1 solution overnight. To...
A 5.0 kg mass hanging from a spring scale is slowly lowered onto a vertical spring, as shown in FIGURE EX9.29. The scale reads in newtons. a. What does the spring scale read just before the mass...
Two 3.0-cm-diameter aluminum electrodes are spaced 0.50 mm apart. The electrodes are connected to a 100 V battery. a. What is the capacitance? b. What is the magnitude of the charge on each electrode?
Light from the sun allows a solar cell to move electrons from the positive to the negative terminal, doing 2.4 10 -19 J of work per electron. What is the emf of this solar cell?
The coefficient of static friction is 0.60 between the two blocks in FIGURE P7.35. The coefficient of kinetic friction between the lower block and the floor is 0.20. Force F causes both blocks to...
Figure Q26.10 shows a 3 V battery with metal wires attached to each end. What are the potential differences ÎV 12 = V 2 - V 1 , ÎV 23 = V 3 - V 2 , ÎV 34 = V 4 - V 3 , and ÎV...
Figure Q26.8 shows a negatively charged electroscope. The gold leaf stands away from the rigid metal post. Is the electric potential of the leaf higher than, lower than, or equal to the potential of...
The electron drift speed in a wire is exceedingly slow typically only a fraction of a millimeter per second. Yet when you turn on a flashlight switch, the light comes on almost instantly. Resolve...
Is Figure Q27.4 a possible surface charge distribution for a current-carrying wire? If so, in which direction is the current? If not, why not? FIGURE Q27.4 ++ ++
The electric field in a 2.0 mm 2.0 mm square aluminum wire is 0.012 V/m. What is the current in the wire?
What electric field strength is needed to create a 5.0 A current in a 2.0-mm-diameter iron wire?
A 0.0075 V/m electric field creates a 3.9 mA current in a 1.0-mm-diameter wire. What material is the wire made of?
Upon what basic quantity does kinetic energy depend? Upon what basic quantity does potential energy depend?
Object A is stationary while objects B and C are in motion. Forces from object A do 10 J of work on object B and 5 J of work on object C. Forces from the environment do 4 J of work on object B and 8...
Can kinetic energy ever be negative? Can gravitational potential energy ever be negative? For each, give a plausible reason for your answer without making use of any equations.
The lowest point in Death Valley is 85 m below sea level. The summit of nearby Mt. Whitney has an elevation of 4420 m. What is the change in potential energy when an energetic 65 kg hiker makes it...
a. What is the kinetic energy of a 1500 kg car traveling at a speed of 30 m/s ( 65 mph)? b. From what height would the car have to be dropped to have this same amount of kinetic energy just before...
Rank in order, from most to least, the elastic potential energy (U Sp ) a to (U Sp ) d stored in the springs of FIGURE Q10.5. Explain. a Compressed d Stretched d 2k Stretched 2d Stretched d FIGURE...
a. With what minimum speed must you toss a 100 g ball straight up to just touch the 10-m-high roof of the gymnasium if you release the ball 1.5 m above the ground? Solve this problem using energy. b....
A spring gun shoots out a plastic ball at speed v 0 . The spring is then compressed twice the distance it was on the first shot. By what factor is the balls speed increased? Explain.
A 55 kg skateboarder wants to just make it to the upper edge of a quarter pipe, a track that is one-quarter of a circle with a radius of 3.0 m. What speed does he need at the bottom?
What minimum speed does a 100 g puck need to make it to the top of a 3.0-m-long, 20 frictionless ramp?
A compressed spring launches a block up an incline. Which objects should be included within the system in order to make an energy analysis as easy as possible?
A pendulum is made by tying a 500 g ball to a 75-cm-long string. The pendulum is pulled 30 to one side, then released. What is the balls speed at the lowest point of its trajectory?
A process occurs in which a systems potential energy decreases while the system does work on the environment. Does the systems kinetic energy increase, decrease, or stay the same? Or is there not...
A particle with the potential energy shown in FIGURE Q10.8 is moving to the right at x = 5 m with total energy E. a. At what value or values of x is this particles speed a maximum? b. Does this...
A 20 kg child is on a swing that hangs from 3.0-m-long chains. What is her maximum speed if she swings out to a 45 angle?
A process occurs in which a systems potential energy increases while the environment does work on the system. Does the systems kinetic energy increase, decrease, or stay the same? Or is there not...
FIGURE Q10.12 is the energy bar chart for a firefighter sliding down a fire pole from the second floor to the ground. Let the system consist of the firefighter, the pole, and the earth. What are the...
The maximum energy a bone can absorb without breaking is surprisingly small. Experimental data show that the leg bones of a healthy, 60 kg human can absorb about 200 J. From what maximum height could...
a. If the force on a particle at some point in space is zero, must its potential energy also be zero at that point? Explain. b. If the potential energy of a particle at some point in space is zero,...
A cannon tilted up at a 30 angle fires a cannon ball at 80 m/s from atop a 10-m-high fortress wall. What is the balls impact speed on the ground below?
In a hydroelectric dam, water falls 25 m and then spins a turbine to generate electricity. a. What is U G of 1.0 kg of water? b. Suppose the dam is 80% efficient at converting the waters potential...
How far must you stretch a spring with k = 1000 N/m to store 200 J of energy?
A stretched spring stores 2.0 J of energy. How much energy will be stored if the spring is stretched three times as far?
A student places her 500 g physics book on a frictionless table. She pushes the book against a spring, compressing the spring by 4.0 cm, then releases the book. What is the books speed as it slides...
A block sliding along a horizontal frictionless surface with speed v collides with a spring and compresses it by 2.0 cm. What will be the compression if the same block collides with the spring at a...
A 10 kg runaway grocery cart runs into a spring with spring constant 250 N/m and compresses it by 60 cm. What was the speed of the cart just before it hit the spring?
As a 15,000 kg jet plane lands on an aircraft carrier, its tail hook snags a cable to slow it down. The cable is attached to a spring with spring constant 60,000 N/m. If the spring stretches 30 m to...
The elastic energy stored in your tendons can contribute up to 35%, of your energy needs when running. Sports scientists find that (on average) the knee extensor tendons in sprinters stretch 41 mm...
The spring in FIGURE EX10.22a is compressed by Îx. It launches the block across a frictionless surface with speed v 0 . The two springs in FIGURE EX10.22b are identical to the spring of Figure...
The spring in FIGURE EX10.23a is compressed by Îx. It launches the block across a frictionless surface with speed v 0 . The two springs in FIGURE EX10.23b are identical to the spring of Figure...