Question: In this problem, you will estimate the

> A high-speed dental drill is rotating at 3.14 × 104 rad/s. Through how many degrees does the drill rotate in 1.00 s?

> Can an astronaut on the Moon use a straw to drink from a normal drinking glass? How about if he pokes a straw through an otherwise sealed juice box? Explain.

> Explain how it is possible that more than half of the molecules in an ideal gas have kinetic energies less than the average kinetic energy. Shouldn't half have less and half have more?

> The sound level 25 m from a loudspeaker is 71 dB. What is the rate at which sound energy is produced by the loudspeaker, assuming it to be an isotropic source?

> A straight, stiff wire of length 1.00 m and mass 25 g is suspended in a magnetic field B = 0.75 T. The wire is connected to an emf. How much current must flow in the wire and in what direction so that the wire is suspended and the tension in the supporti

> A sound wave in room-temperature air has an intensity level of 65.0 dB and a frequency of 131 Hz. (a) What is the pressure amplitude? (b) What is the displacement amplitude?

> A bicycle and its rider together have a mass of 75 kg. What power output of the rider is required to maintain a constant speed of 4.0 m/s (about 9 mi/h) up a 5.0% grade (a road that rises 5.0 m for every 100 m along the pavement)? Assume that frictional

> In the figure, switch S is initially open. It is closed, and then opened again a few seconds later. (a) In what direction does current flow through the ammeter when switch S is closed? (b) In what direction does current flow when switch S is then opene

> What is the mass of one gold atom in kilograms?

> A circuit has a resistor and an unknown component in series with a 12 V (rms) sinusoidal ac source. The current in the circuit decreases by 20% when the frequency decreases from 240 Hz to 160 Hz. What is the second component in the circuit? Explain your

> Two speakers spaced a distance 1.5 m apart emit coherent sound waves at a frequency of 680 Hz in all directions. The waves start out in phase with each other. A listener walks in a circle of radius greater than 1 m centered on the midpoint of the two spe

> 1. An electron, passing close to a target nucleus, slows and radiates away some of its energy. What is this process called? (a) Compton effect (b) photoelectric effect (c) bremsstrahlung (d) blackbody radiation (e) stimulated emission 2. How many emissi

> A pendulum is made from a uniform rod of mass m1 and a small block of mass m2 attached at the lower end. (a) If the length of the pendulum is L and the oscillations are small, find the period of the oscillations in terms of m1, m2, L, and g. (b) Check

> Explain why electric field lines begin on positive charges and end on negative charges. [Hint: What is the direction of the electric field near positive and negative charges?]

> A biologist is studying plant growth and wants to simulate a gravitational field twice as strong as Earth’s. She places the plants on a horizontal rotating table in her laboratory on Earth at a distance of 12.5 cm from the axis of rotat

> Explain why any net charge on a solid metal conductor in electrostatic equilibrium is found on the outside surface of the conductor instead of being distributed uniformly throughout the solid.

> What makes clothes cling together—or to your body—after they’ve been through the dryer? Why do they not cling as much if they are taken out of the dryer while slightly damp? In which case would you expect your clothes to cling more, all other things bein

> A wooden barrel full of water has a flat circular top of radius 25.0 cm with a small hole in it. A tube of height 8.00 m and inner radius 0.250 cm is suspended above the barrel with its lower end inserted snugly in the hole. Water is poured into the uppe

> Two children are playing with a tin-can telephone. The children are 12 m apart, the string connecting their tin cans has a linear mass density of 1.3 g/m, and it is stretched with a tension of 8.0 N. One child decides to pluck the string. How long does i

> A proposed “space elevator” consists of a cable going all the way from the ground to a space station in geostationary orbit (always above the same point on Earth’s surface). Elevator “cars” would climb the cable to transport cargo to outer space. Conside

> A convex mirror produces an image located 18.4 cm behind the mirror when an object is placed 32.0 cm in front of the mirror. What is the focal length of this mirror?

> At t = 0, six birds are flying south at 10 m/s. Their masses and their velocities at a later time are: (a) 200 g, 10 m/s north at t = 30 s (b) 200 g, 10 m/s east at t = 30 s (c) 200 g, 20 m/s north at t = 60 s (d) 400 g, 20 m/s north at t = 60 s (e) 400

> A cup of hot coffee has been poured, but the coffee drinker has a little more work to do at the computer before she picks up the cup. She intends to add some milk to the coffee. To keep the coffee hot as long as possible, should she add the milk at once,

> In a circus trapeze act, two acrobats fly through the air and grab on to each other, then together grab a swinging bar. One acrobat, with a mass of 60 kg, is moving at 3.0 m/s at an angle of 10° above the horizontal, and the other, with a mass of 80 kg,

> Two factors that can determine the distance over which a force can act are the mass of the exchange particle that carries the force and the Heisenberg uncertainty principle [Eq. (28-5)]. Assume that the uncertainty in the energy of an exchange particle i

> When the temperature as measured in °C of a radiating object is doubled (such as a change from 20°C to 40°C), is the radiation rate necessarily increased by a factor of 16?

> A 5.0 mH inductor and a 10.0 Q resistor are connected in series with a 6.0 V dc battery. (a) What is the voltage across the resistor immediately after the switch is closed? (b) What is the voltage across the resistor after the switch has been closed fo

> At very low temperatures, the molar specific heat of hydrogen (H2) is CV = 1.5R. At room temperature, CV = 2.5R. Explain.

> Calculate the value of (a) Planck's constant and (b) the work function of the metal from the data obtained by Robert A. Millikan in 1916, as shown in the graph. Millikan was attempting to disprove Einstein's photoelectric equation; instead he found tha

> Explain why two waves of significantly different frequencies cannot be coherent.

> Medical testing has established that the maximum acceleration a pilot can be subjected to without losing consciousness is approximately 5.0g if the axis of acceleration is aligned with the spine. (See Example 5.4.) A pilot can avoid “blackout” at acceler

> Why can a neutron within a nucleus be stable, whereas an isolated neutron is unstable? What determines whether a neutron within a nucleus is stable? [Hint: Consider conservation of energy.]

> At what time is the current in the inductor 0.0010 times its initial value?

> A spy satellite is in circular orbit around Earth. It makes one revolution in 6.00 h. (a) How high above Earth’s surface is the satellite? (b) What is the satellite’s acceleration?

> A velodrome is built for use in the Olympics. The radius of curvature of the surface is 20.0 m. At what angle should the surface be banked for cyclists moving at 18 m/s? (Choose an angle so that no frictional force is needed to keep the cyclists in their

> A square loop of wire, 0.75 m on each side, has one edge along the positive z-axis and is tilted toward the yz-plane at an angle of 30.0° with respect to the horizontal (xz-plane). There is a uniform magnetic field of 0.32 T pointing in the po

> Explain why the molar specific heat of a diatomic gas such as O2 is larger than that of a monatomic gas such as Ne.

> A room air conditioner causes a temperature change of −6.0°C. (a) What is the temperature change in kelvins? (b) What is the temperature change in °F?

> Repeat Problem 37 for an operating frequency of 98.7 Hz. (a) What is the phase angle for this circuit? (b) Draw the phasor diagram. (c) What is the resonant frequency for this circuit?

> Approximately what is the total energy of the neutrino emitted when / decays by electron capture?

> While an elevator of mass 2530 kg moves upward, the tension in the cable is 33.6 kN. (a) What is the acceleration of the elevator? (b) If at some point in the motion the velocity of the elevator is 1.20 m/s upward, what is the elevator’s velocity 4.00 s

> An electric mixer is being used to mix up some cake batter. What happens to the motor if the batter is too thick, so the beaters are turning slowly?

> In Section 25.3 we studied interference due to thin films. Why must the film be thin? Why don't we see interference effects when looking through a window or at a poster covered by a plate of glass—even if the glass is optically flat?

> Can sound waves be polarized? Explain.

> An electron (charge −e) is projected horizontally into the space between two oppositely charged parallel plates. The electric field between the plates is 500.0 N/C upward. If the vertical deflection of the electron as it leaves the plates has magnitude 3

> Think of a wire of length L as two wires of length L/2 in series. Construct an argument for why the resistance of a wire must be proportional to its length.

> A battery is connected to a clock by copper wires as shown. What is the direction of current through the clock (B to C or C to B)? What is the direction of current through the battery (D to A or A to D)? Which terminal of the battery is at the higher pot

> Some batteries can be “recharged.” Does that mean that the battery has a supply of charge that is depleted as the battery is used? If “recharging” does not literally mean to put char

> To resolve details of a cell using an ordinary microscope, you must use a wavelength that is about the same size, or smaller, than the details of the cell you want to observe. Suppose you want to be able to see the ribosomes, which are about 20 nm in dia

> 11. An object is in nonuniform circular motion with constant angular acceleration. Identify the correct statement(s). (Use the same answer choices as in Question 10.) (a) 1 only (b) 2 only (c) 3 only (d) 1, 2, and 3 (e) 2 and 3 (f) 1 and 2 (g) 1 and 3 (h

> A motorist driving a 1200 kg car on level ground accelerates from 20.0 m/s to 30.0 m/s in a time of 5.0 s. Ignoring friction and air resistance, determine the average mechanical power in watts the engine must supply during this time interval.

> A parallel plate capacitor has a charge of 0.020 µC on each plate with a potential difference of 240 V. The parallel plates are separated by 0.40 mm of air. (a) What is the capacitance for this capacitor? (b) What is the area of a single plate? (c) At

> When the viola section of an orchestra with six members plays together, is the sound 6 times as loud as when a single viola plays? Explain. Is the intensity 6 times what it would be for a single viola? [Hint: The six sound waves are not coherent.]

> Why don't you see an interference pattern on your desk when you have light from two different lamps illuminating the surface?

> Derivation of the Doppler formula for light. A source and observer of EM waves move relative to each other at velocity v. Let v be positive if the observer and source are moving apart from each other. The source emits an EM wave at frequency fs (measured

> A pion (mass 0.140 GeV/c2) at rest decays by the weak interaction into a muon of mass 0.106 GeV/c2 and a muon antineutrino: What is the total kinetic energy of the muon and the antineutrino?

> A spring of negligible mass is compressed between two blocks, A and B, which are at rest on a frictionless horizontal surface at a distance of 1.0 m from a wall on the left and 3.0 m from a wall on the right. The sizes of the blocks and spring are small.

> A variable capacitor is made of two parallel semicircular plates with air between them. One plate is fixed in place and the other can be rotated. The electric field is zero everywhere except in the region where the plates overlap. When the plates are dir

> What is the average linear speed of Earth about the Sun?

> A 1500 kg car coasts in neutral down a 2.0° hill. The car attains a terminal speed of 20.0 m/s. (a) How much power must the engine deliver to drive the car on a level road at 20.0 m/s? (b) If the maximum useful power that can be delivered by the engine

> The figure shows standing wave patterns in five pipes of equal length. Pipes (c) and (e) are open at both ends; the others are closed at one end. Rank the standing waves in order of the frequency, largest to smallest.

> Rhonda keeps a 2.0 kg model airplane moving at constant speed in a horizontal circle at the end of a string of length 1.0 m. The tension in the string is 18 N. How much work does the string do on the plane during each revolution?

> A charged pion can decay either into a muon or an electron. The two decay modes of a π− are: / And / . Write the two decay modes for the π+. [Hint: π+ is the antiparticle of π−. Replace each particle in the decay reaction with its corresponding antipa

> A coil of wire is connected to an ideal 6.00 V battery at t = 0. At t = 10.0 ms, the current in the coil is 204 mA. One minute later, the current is 273 mA. Find the resistance and inductance of the coil. [Hint: Sketch I(t).]

> A police car’s radar gun emits microwaves with a frequency of f1 = 36.0 GHz. The beam reflects from a speeding car, which is moving away at 43.0 m/s with respect to the police car. The frequency of the reflected microwave as observed by the police is f2.

> A bicycle wheel, of radius 0.30 m and mass 2 kg (concentrated on the rim), is rotating at 4.00 rev/s. After 50 s the wheel comes to a stop because of friction. What is the magnitude of the average torque due to frictional forces?

> A spherical balloon with a radius of 12.0 cm is filled with helium. The bottom of the balloon is attached to a 2.30 m length of ribbon that is anchored to the ground. The balloon alone has a mass of 2.80 × 10−3 kg. Ignore the mass of the ribbon. (a) Wha

> The figure shows a magnetic dipole antenna transmitting an electromagnetic wave. At a point P far from the antenna, what are the directions of the electric and magnetic fields of the wave?

> A bird perched on a power line is not harmed, but if you are pruning a tree and your metal pole saw comes in contact with the same wire, you risk being electrocuted. Explain.

> A negatively charged particle of mass 5.00 × 10−19 kg is moving with a speed of 35.0 m/s when it enters the region between two parallel capacitor plates. The initial velocity of the charge is parallel to the plate surfaces

> When a coin is tossed directly upward, what can you say about its velocity and acceleration at the high point of the toss?

> A container is filled with gas at a pressure of 4.0 × 105 Pa. The container is a cube, 0.10 m on a side, with one side facing south. What is the magnitude and direction of the force on the south side of the container due to the gas inside?

> A fisherman notices a buoy bobbing up and down in the water in ripples produced by waves from a passing speedboat. These waves travel at 2.5 m/s and have a wavelength of 7.5 m. At what frequency does the buoy bob up and down?

> An RLC circuit has a resistance of 10.0 Ω, an inductance of 15.0 mH, and a capacitance of 350 µF. By what factor does the impedance of this circuit change when the frequency at which it is driven changes from 60 Hz to 120 Hz? Does the impedance increase

> An electrician working on “live” circuits wears insulated shoes and keeps one hand behind his or her back. Why?

> What average force is necessary to bring a 50.0 kg sled from rest to a speed of 3.0 m/s in a period of 20.0 s? Assume frictionless ice.

> While I1 is increasing, does current flow in loop 2? If so, does it flow clockwise or counterclockwise as viewed from the right? Explain.

> A packing carton slides down an inclined plane of angle 30.0° and of incline length 2.0 m. (a) If the initial speed of the carton is 4.0 m/s directed down the incline, what is the speed at the bottom? Ignore friction. (b) How long does it take the cart

> Verify that the collision between the proton and the nitrogen nucleus in Example 26.4 is elastic.

> A dentist holds a small mirror 1.9 cm from a surface of a patient's tooth. The image formed is upright and 5.0 times as large as the object. (a) Is the image real or virtual? (b) What is the focal length of the mirror? Is it concave or convex? (c) If

> A beam of neutrons is used to study molecular structure through a series of diffraction experiments. A beam of neutrons with a wide range of de Broglie wavelengths comes from the core of a nuclear reactor. In a time-offlight technique, used to select neu

> Refer to the pulse in Problem 9. (a) What is the speed of propagation of the pulse? (b) At what average speed does the point at x = 2.0 m move during this time interval?

> You decide to test your physics knowledge while going over a waterfall in a barrel. You take a baseball into the barrel with you, and as you are falling vertically downward, you let go of the ball. What do you expect to see for the motion of the ball rel

> The activity of a sample containing radioactive 108Ag is 6.4 × 104 Bq. Precisely 12 min later, the activity is 2.0 × 103 Bq. Calculate the half-life of 108Ag.

> A lens (n = 1.52) is coated with a magnesium fluoride film (n = 1.38). (a) If the coating is to cause destructive interference in reflected light for λ = 560 nm (the peak of the solar spectrum), what should its minimum thickness be? (b) At what two wav

> In an accelerator, two protons with equal kinetic energies collide head-on. The following reaction takes place: . What is the minimum possible kinetic energy of each of the incident proton beams?

> The magnetic flux through a flat surface is known. The area of the surface is also known. Is that information enough to calculate the average magnetic field on the surface? Explain.

> During a walk on the Moon, an astronaut accidentally drops his camera over a 20.0 m cliff. It leaves his hands with zero speed, and after 2.0 s it has attained a velocity of 3.3 m/s downward. How far has the camera fallen after 4.0 s?

> A 10.0 kg block is released from rest on a frictionless track inclined at an angle of 55°. (a) What is the net force on the block after it is released? (b) What is the acceleration of the block? (c) If the block is released from rest, how long will it

> Is it more dangerous to touch a “live” electric wire when your hands are dry or wet, everything else being equal? Explain.

> Questions 1–4: A satellite in orbit travels around Earth in uniform circular motion. In the figure, the satellite moves counterclockwise (ABCDA). Answer choices: (a) +x (b) +y (c) −x (d) −y (e) 45&Aci

> The photoelectric effect is studied using a tungsten target. The work function of tungsten is 4.5 eV. The incident photons have energy 4.8 eV. (a) What is the threshold frequency? (b) What is the stopping potential? (c) Explain why, in classical physi

> Why are astronomical observatories often located on mountaintops?

> Why are ammeters connected in series with a circuit element in which the current is to be measured and voltmeters connected in parallel across the element for which the potential difference is to be measured?

> When helium weather balloons are released, they are purposely underinflated. Why? [Hint: The balloons go to very high altitudes.]

> An object hanging vertically from a spring and a simple pendulum both have a period of oscillation of 1 s on Earth. An astronaut takes the two devices to another planet where the gravitational field is stronger than that of Earth. For each of the two sys

> The rogue starship Galaxa is being chased by the battle cruiser Millenia. The Millenia is catching up to the Galaxa at a rate of 0.55c when the captain of the Millenia decides it is time to fire a missile. First the captain shines a laser range finder to

> One cold and windy winter day, Zach notices a humming sound coming from his chimney, which is open at the top and closed at the bottom. He opens the chimney at the bottom and notices that the sound changes. He goes over to the piano to try to match the n

> Is the electric field inside a conductor always zero? If not, when is it not zero? Explain.

> If E = 0 everywhere throughout a region of space, what do we know is true about the potential at points in that region?