An overhead transmission cable for electrical power is 2000 m long and consists of two parallel copper wires, each encased in insulating material. A short circuit has developed somewhere along the...

A 25 kg box sliding to the left across a horizontal surface is brought to a halt in a distance of 35 cm by a horizontal rope pulling to the right with 15 N tension. How much work is done by (a)...

A particle moving to the left is slowed by a force pushing to the right. Is the work done on the particle positive or negative? Or is there not enough information to tell? Explain.

A 2.0 kg book is lying on a 0.75-m-high table. You pick it up and place it on a bookshelf 2.25 m above the floor. a. How much work does gravity do on the book? b. How much work does your hand do on...

A 20 g particle is moving to the left at 30 m/s. A force on the particle causes it to move the the right at 30 m/s. How much work is done by the force?

You throw a 5.5 g coin straight down at 4.0 m/s from a 35-m-high bridge. a. How much work does gravity do as the coin falls to the water below? b. What is the speed of the coin just as it hits the...

The two ropes seen in FIGURE EX9.18 are used to lower a 255 kg piano 5.00 m from a second-story window to the ground. How much work is done by each of the three forces? 1830 N 60% 1295 N 45 2500 N...

FIGURE EX9.20 is the force-versus-position graph for a particle moving along the x-axis. Determine the work done on the particle during each of the three intervals 01 m, 12 m, and 23 m. F, (N) 4 -x...

A pressure of 10 MPa is applied to 0.25 m 3 of a liquid, causing a volume reduction of 0.005 cm 3 . Determine the bulk modulus of elasticity.

An object is thrown straight up into the air and feels no air resistance. How can the object have an acceleration when it has stopped moving at its highest point?

You are on the west bank of a river that is flowing north with a speed of 1.2 m/s. Your swimming speed relative to the water is 1.5 m/s, and the river is 60 m wide. What is your path relative to the...

A helium balloon hovers in midair, neither ascending nor descending. Is it in equilibrium? What forces act on it?

Some people say that the force of inertia (or force of momentum) throws the passengers forward when a car brakes sharply. What is wrong with this explanation?

(a) An ordinary flea has a mass of 210 g. How many newtons does it weigh? (b) The mass of a typical froghopper is 12.3 mg. How many newtons does it weigh? (c) A house cat typically weighs 45 N. How...

A small car of mass 380 kg is pushing a large truck of mass 900 kg due east on a level road. The car exerts a horizontal force of 1600 N on the truck. What is the magnitude of the force that the...

When a string barely strong enough lifts a heavy weight, it can lift the weight by a steady pull; but if you jerk the string, it will break. Explain in terms of Newtons laws of motion.

Boxes A and B are connected to each end of a light vertical rope (Fig. P4.49). A constant upward force F = 80.0 N is applied to box A. Starting from rest, box B descends 12.0 m in 4.00 s. The tension...

You throw a baseball straight upward. If you do not ignore air resistance, how does the time required for the ball to reach its maximum height compare to the time required for it to fall from its...

A flywheel rotates with constant angular velocity. Does a point on its rim have a tangential acceleration? A radial acceleration? Are these accelerations constant in magnitude? In direction? In each...

When you stand with bare feet in a wet bathtub, the grip feels fairly secure, and yet a catastrophic slip is quite possible. Explain this in terms of the two coefficients of friction.

You are balancing a wrench by suspending it at a single point. Is the equilibrium stable, unstable, or neutral if the point is above, at, or below the wrenchs center of gravity? In each case give the...

Certain features of a person, such as height and mass, are fixed (at least over relatively long periods of time). Are the following features also fixed? (a) Location of the center of gravity of the...

When sound travels from air into water, does the frequency of the wave change? The speed? The wavelength? Explain your reasoning.

A 60.0-m-long brass rod is struck at one end. A person at the other end hears two sounds as a result of two longitudinal waves, one traveling in the metal rod and the other traveling in air. What is...

Many automobile engines have cast-iron cylinders and aluminum pistons. What kinds of problems could occur if the engine gets too hot? (The coefficient of volume expansion of cast iron is...

Why do frozen water pipes burst? Would a mercury thermometer break if the temperature went below the freezing temperature of mercury? Why or why not?

Why is it sometimes possible to loosen caps on screw-top bottles by dipping the capped bottle briefly into hot water?

A student asserts that a suitable unit for specific heat is 1 m 2 /s 2 C. Is she correct? Why or why not?

When you first step out of the shower, you feel cold. But as soon as you are dry you feel warmer, even though the room temperature does not change. Why?

A brass rod 12.0 cm long, a copper rod 18.0 cm long, and an aluminum rod 24.0 cm longeach with cross-sectional area 2.30 cm 3 are welded together end to end to form a rod 54.0 cm long, with copper as...

During your mechanical engineering internship, you are given two uniform metal bars A and B, which are made from different metals, to determine their thermal conductivities. Measuring the bars, you...

It is not correct to say that a body contains a certain amount of heat, yet a body can transfer heat to another body. How can a body give away something it does not have in the first place?

When you blow on the back of your hand with your mouth wide open, your breath feels warm. But if you partially close your mouth to form an o and then blow on your hand, your breath feels cool. Why?

In a hospital, pure oxygen may be delivered at 50 psi (gauge pressure) and then mixed with N 2 O. What volume of oxygen at 20C and 50 psi (gauge pressure) should be mixed with 1.7 kg of N 2 O to get...

The two sides of the DNA double helix are connected by pairs of bases (adenine, thymine, cytosine, and guanine). Because of the geometric shape of these molecules, adenine bonds with thymine and...

A student asked, Since electrical potential is always proportional to potential energy, why bother with the concept of potential at all? How would you respond?

If E(vector) is zero throughout a certain region of space, is the potential necessarily also zero in this region? Why or why not? If not, what can be said about the potential?

During lightning strikes from a cloud to the ground, currents as high as 25,000 A can occur and last for about 40 ms. How much charge is transferred from the cloud to the earth during such a strike?

Can the potential difference between the terminals of a battery ever be opposite in direction to the emf ? If it can, give an example. If it cannot, explain why not.

Nerve cells transmit electric signals through their long tubular axons. These signals propagate due to a sudden rush of Na + ions, each with charge +e, into the axon. Measurements have revealed that...

Two 120-V light bulbs, one 25-W and one 200-W, were connected in series across a 240-V line. It seemed like a good idea at the time, but one bulb burned out almost immediately. Which one burned out,...

A real battery, having nonnegligible internal resistance, is connected across a light bulb as shown in Fig. Q26.10. When the switch S is closed, what happens to the brightness of the bulb? Why?...

In the circuit shown in Fig. E26.18, ε = 36.0 V, R 1 = 4.00 Ω, R 2 = 6.00 Ω, and R 3 = 3.00 Ω. (a) What is the potential difference V ab between...

A 6.00 F capacitor that is initially uncharged is connected in series with a 5.00 resistor and an emf source with = 50.0 V and negligible internal resistance. At the instant when the resistor is...

In a Hall-effect experiment, is it possible that no transverse potential difference will be observed? Under what circumstances might this happen?

In a cyclotron, the orbital radius of protons with energy 300 keV is 16.0 cm. You are redesigning the cyclotron to be used instead for alpha particles with energy 300 keV. An alpha particle has...

To use a larger sample, the experimenters construct a solenoid that has the same length, type of wire, and loop spacing but twice the diameter of the original. How does the maximum possible magnetic...

The current in the long, straight wire AB shown in Fig. E29.7 is upward and is increasing steadily at a rate di/dt. (a) At an instant when the current is i, what are the magnitude and direction of...

A rectangular loop of wire with dimensions 1.50 cm by 8.00 cm and resistance R = 0.600 Ω is being pulled to the right out of a region of uniform magnetic field. The magnetic field has...

A 0.250-m-long bar moves on parallel rails that are connected through a 6.00-Ω resistor, as shown in Fig. E29.33, so the apparatus makes a complete circuit. You can ignore the resistance...

Consider the circuit in Exercise 30.23. (a) Just after the circuit is completed, at what rate is the battery supplying electrical energy to the circuit? (b) When the current has reached its final...

The signal from the oscillating electrode is fed into an amplifier, which reports the measured voltage as an rms value, 1.5 nV. What is the potential difference between the two extremes? (a) 1.5 nV;...

Light requires about 8 minutes to travel from the sun to the earth. Is it delayed appreciably by the earths atmosphere? Explain.

Sunlight or starlight passing through the earths atmosphere is always bent toward the vertical. Why? Does this mean that a star is not really where it appears to be? Explain.

A beam of light goes from one material into another. On physical grounds, explain why the wavelength changes but the frequency and period do not.

A student claimed that, because of atmospheric refraction (see Discussion Question Q33.2), the sun can be seen after it has set and that the day is therefore longer than it would be if the earth had...

When a sheet of plastic food wrap is placed between two crossed polarizers, no light is transmitted. When the sheet is stretched in one direction, some light passes through the crossed polarizers....

Ordinary glasses are worn in front of the eye and usually 2.0 cm in front of the eyeball. Suppose that the person in Exercise 34.52 prefers ordinary glasses to contact lenses. What focal length...

A person with a near point of 85 cm, but excellent distant vision, normally wears corrective glasses. But he loses them while traveling. Fortunately, he has his old pair as a spare. (a) If the lenses...

A researcher measures the thickness of a layer of benzene (n = 1.50) floating on water by shining monochromatic light onto the film and varying the wavelength of the light. She finds that light of...

An investigator proposes to study the mass-transfer process for the dissolution of a single solid sphere suspended within a turbulent flow stream. Predict the variables that would be used to explain...

Using the expression for the gradient in polar coordinates (Appendix A), find the gradient of (r, ) when Where is the gradient maximum? The terms A and a are constant. a V = Ar sin 0( 1

Determine the diameter of the glass tube necessary to keep the capillary-height change of water at 30C less than 1 mm.

In Problem 2.2, find the depth at which the net force on the tank is zero. Data From Problem 2.2 The open end of a cylindrical tank 2 ft in diameter and 3 ft high is submerged in water as shown. If...

Determine the depth change to cause a pressure increase of 1 atm for (a) water, (b) sea water (SG = 1.0250), and (c) mercury (SG = 13.6).

The velocities in a circular duct of 20-in. diameter were measured as follows: Find (a) the average velocity; (b) the flow rate in cubic feet per second. Velocity Distance from Velocity Distance from...

A stationary jet engine is shown. Air with a density of 0.0805 lb/ft 3 enters as shown. The inlet and outlet cross sectional areas are both 10.8 ft 2 . The mass of fuel consumed is 2% of the mass of...

a. Determine the magnitude of the x and y components of the force exerted on the fixed blade shown by a 3-ft 3 /s jet of water flowing at 25 fps. b. If the blade is moving to the right at 15 fps,...

The pump in the boat shown pumps 6 ft 3 /s of water through a submerged water passage, which has an area of 0.25 ft 2 at the bow of the boat and 0.15 ft 2 at the stern. Determine the tension in the...

At the end of a water pipe of 3-in. diameter is a nozzle that discharges a jet having a diameter of 1 1/2 in into the open atmosphere. The pressure in the pipe is 60 psig (pounds per square inch...

If the plate shown is inclined at an angle as shown, what are the forces F x and F y necessary to maintain its position? The flow is friction less. 4 3 v = 100 fps - Fx m = 2 slugs/s Fy

Consider the differential control volume shown below. By applying the conservation of mass and the momentum theorem, show that dP + pv dv + g dy = 0 2, 2 V2, A2 s (1) P1, P1 V1, A1

For the pipe-flow-reducing section D 1 = 8 cm, D 2 = 5 cm, and p 2 = 1 atm. If v 1 = 5 m/s and the manometer reading is h = 58 cm, estimate the total force resisted by the flange bolts. Water Hg

The velocity profile in the annular control volume of Example 3 is approximately linear, varying from a velocity of zero at the outer boundary to a value of d/2 at the inner boundary. Develop an...

Sea water, p = 1025 kg/m 3 , flows through a pump at 0:21 m 3 /s. The pump inlet is 0.25 m in diameter. At the inlet the pressure is -0.15 m of mercury. The pump outlet, 0.152 m in diameter, is 1.8 m...

Air at 70F, Flows into a 10-ft 3 reservoir at a velocity of 110 fps. If the reservoir pressure is 14 psig and the reservoir temperature 70F, find the rate of temperature increase in the reservoir....

Water flows through a 2-in.-diameter horizontal pipe at a flow rate of 35 gal/min. The heat transfer to the pipe can be neglected, and frictional forces result in a pressure drop of 10 psi. What is...

During the test of a centrifugal pump, a Bourdon pressure gage just outside the casing of the 12-in.-diameter suction pipe reads -6 psig (i.e., vacuum). On the 10-in.-diameter discharge pipe, another...

A liquid flows from A to B in a horizontal pipe line shown at a rate of 3 ft 3 /s with a friction loss of 0.45 ft of flowing fluid. For a pressure head at B of 24 in., what will be the pressure head...

Water at 100°C flows through a 10 cm diameter pipe that has a 180 degree vertical turn as shown in the figure below. The volumetric flow rate is constant at 0.2 m 3 /s. The absolute pressure at...

A Venturi meter with an inlet diameter of 0.6 m is designed to handle 6 m 3 /s of standard air. What is the required throat diameter if this flow is to give a reading of 0.10 m of alcohol in a...

An automobile is driving into a 45-mph headwind at 40 mph. If the barometer reads 29 in. Hg and the temperature is 40F, what is the pressure at a point on the auto where the wind velocity is 120 fps...

A fan draws air from the atmosphere through a 0.30-m diameter round duct that has a smoothly rounded entrance. A differential manometer connected to an opening in the wall of the duct shows a vacuum...

Find the change in temperature between stations (1) and (2) in terms of the quantities A 1 , A 3 , v 1 , v 3 , c v , and θ. The internal energy is given by c v T . The fluid is water and...

The solution to 5.22 is Show that Bernoulli's equation applied between sections 1 and 2 does not give this result. Derive all expressions for the change in total head across a hydraulic jump. 1/2 h...

Residential water use, exclusive of fire protection, runs about 80 gallons per person per day. If the water is delivered to a residence at 60 psig, estimate the monthly energy required to pump the...

A 1968 Volkswagen sedan is driving over a 7300-ft-high mountain pass at a speed of v m/s into a headwind of W m/s. Compute the gage pressure in mPa at a point on the auto where the velocity relative...

A liquid is heated in a vertical tube of constant diameter, 15 m long. The flow is upward. At the entrance the average velocity is 1 m/s, the pressure 340,000 Pa, and the density is 1001 kg/m 3 . If...

For fully developed turbulent flow over a flat plate of length L, the local Sherwood number at position x(0 < x ¤ L) is estimated by Develop an expression for the average Sh over length L of...

In Problem 6.26, compute the upward force on the device from water and air. Use the results of Problem 6.26 as well as any other data given in that problem that you may need. Explain why you cannot...

Water is discharged from a 1.0-cm-diameter nozzle that is inclined at a 30° angle above the horizontal. If the jet strikes the ground at a horizontal distance of 3.6 m and a vertical distance of...

In the previous problem, determine the flow rate at which the pump inlet pressure is equal to the vapor pressure of the water. Assume that friction causes a head loss of 4 ft. The vapor pressure of...

Water flows through the pipe contraction shown at a rate of 1 ft 3 /s. Calculate the differential manometer reading in inches of mercury, assuming no energy loss in the flow. Be sure to give the...

Consider a 4-cm pipe that runs between a tank open to the atmosphere and a station open to the atmosphere 10 m below the water surface in the tank. Assuming friction less flow, what will be the mass...

A fluid of density Ï 1 enters a chamber where the fluid is heated so that the density decreases to Ï 2 The fluid then escapes through a vertical chimney that has a height L. Neglecting...

Find Dv/Dt in polar coordinates by taking the derivative of the velocity. (v = v r (r, , t)e r + v (r, , t)e . Remember that the unit vectors have derivatives.)

Does the velocity distribution in Example 2 satisfy continuity?

The atmospheric density may be approximated by the relation = 0 exp(-y/), where = 22,000 ft. Determine the rate at which the density changes with respect to body falling at v fps. If v = 20,000...

In polar coordinates, the continuity equation is Show that a. if v θ = 0, then v r = F(θ)/r b. if v r = 0, then v θ = f(r) |1 1 (rv,) +- r 0 r

Obtain the equations for a one-dimensional steady, viscous, compressible flow in the x direction from the Navier Stokes equations. (These equations, together with an equation of state and the energy...