Physics Lecture Demonstrations
Demonstrations suggested for the text
Halliday & Resnick Fundaments of Physics, 9th edition, by
Revised Fri Aug 12 10:19:21 2011
||Movie--Powers of Ten
||"Powers of Ten" is a 9 minute film spanning scales from the edge of the universe to the sub-atomic
||A replica of the platinum-iridium bar in Paris that was the international standard for length before 1960.
||One Nanosecond Bar
||A piece of plastic cut to a 1 ns length and imprinted "one nanosecond." Ruler shown for comparison.
Chapter2--Motion Along a Straight Line
||Motion Detector and Board
||An ultrasonic motion detector generates a real-time graph of displacement (and/or veloctiy and/or acceleration) versus time as a boards is moved in front of the detector.
||Linear Air Track: Position vs. Time
||A glider travels down the 5 m air track while evenly spaced photogates record the elapsed time. One can then plot the position versus time for the glider on an overhead. The track may be inclined for uniformly accelerated motion.
||Linear Air Track: Instantaneous Velocity
||An air track glider passes through two pairs of closely spaced photogates with each pair separated by 2 meters, enabling instantaneous velocities, accelerations, and predicted distances to be calculated.
||Video: 405 the movie
||2000 film showing plan making emergency landing on top of Jeep: http://www.405themovie.com/. (For amusement purposes)
||Inclined Air Track
||Prop up one end on an air track and use photogates to time the glider's voyage.
||Dime and Feather Tube
||A penny and a feather fall freely inside a glass cylinder that can be evacuated.
||Timed Free Fall -- Lecture Hall
||A metal ball is dropped from 1m and then from 4m into a catch bucket; a precise digital timer records the time of flight for each fall. [May conflict with Shoot-the-Monkey or Timed Free Fall.]
||Magnetic Blackboard Vectors
||A set of magnet-backed vectors of lengths 3, 4, and 5 used to show vector addition on the blackboard.
Chapter4--Motion in Two and Three Dimensions
||Shoot the Monkey
||An air-gun shoots at a monkey, released when the air-gun is fired; the bullet hits the monkey in mid-air. [May conflict with Timed Free Fall or Balls Shot and Dropped.]
||Jumping Ball on Cart
||A ball projected vertically upward from a wheeled cart falls back into the muzzle.
||Balls Shot and Dropped -- Lecture Hall
||A ball is dropped and simultaneously another is projected horizontally; they hit the floor at the same time. [May conflict with Shoot-the-Monkey and Timed Free Fall.]
||Range of a Gun
||Shoot at 45, then calculate 30 or 60 and place the target
||Balls on Rotating Disk
||A disc with two balls mounted at different radii rotates at varying speeds. A third ball may be placed in the center if disk is horizontally mounted. Both orbital and spin rotations may be seen.
||Crossing the River
||A battery powered tank runs at constant speed on a sheet of paper that is pulled in a direction perpendicular to the tank's velocity.
Chapter5--Force and Motion -- I
||A 100 g mass is suspended from a 1 kg mass which is suspended from a crossbar. A sharp downward pull breaks the lower thread; a slow pull the upper thread.
||Yank a tablecloth from under a bottle of wine, beer, and a book.
||The bottommost of a stack of blocks, when struck sharply, will slide to the side while the upper blocks remain in place.
||Loose Hammer Head
||The head of a hammer will remain in place when the handle is struck from above or below.
||Block on a Cart
||A block is placed on a rolling cart; when the cart is stopped, the block continues.
||Second Law--Fan Propelled Cart
||Launch a fan-propelled (constant acceleration) cart down the track and observe what happens when its mass is varied.
||Dynamics Cart with Force and Motion Sensors
||Use a motion sensor with a force sensor mounted on a dynamics cart pulled by a constant tension string to illustrate Newton's second law. The mass of the cart and the string tension can be varied.
||Bend the Wall
||Push on a concrete wall and the wall's deflection is detected by the deflection of a laser beam
||3rd Law with Scales
||Pull on two coupled spring scales with springs of equal or unequal strength.
||3rd Law with Bathroom Scales
||Have two students push against bathroom scales laid back-to-back to verify that each scale reads the same.
||Push Me Pull Me Carts
||Two people stand on roller carts and both pull on a rope or push with a long stick.
||Fan Cart with Sail
||A cart with a sail propelled by a battery powered fan shows interesting third law behavior.
||Tennis Ball Cannon
||A cannon mounted on an air track glider shoots out a tennis ball horizontallly.
||Two equal masses are hung from a pulley. A small amount of mass is transferred from one side to the other.
||Suspended 3-4-5 Block
||A 1 kg mass rests on a 3-4-5 incline (e.g. incline angle = arctan(3/4)). Forces parallel and perpendicular to the incline will support the mass in mid-air when the incline is removed.
||Tension in a String
||The weight of a mass hung from a spring scale is compared to the weight shown on a spring scale between two masses over pulleys
||A mass is hung at the end of a series of spring scales with an intervening mass.
||Rope and three students
||Two large strong students pull on the ends of a rope and a small student pushes down in the middle.
Chapter6--Force and Motion -- II
||Friction Cars on Inclined Plane
||The static or dynamic forces required to move teflon-coated, rubber-coated, and wooden carts on an inclined plan are displayed on a spring scale
||Coffee Filter Drop
||One coffee filter dropped from one meter and four coffee filters dropped from 2 meters hit the ground at the same time, demonstrating that the drag force is proportional to the square of the velocity
||This consists of a large and a small ball attached to opposite ends of a string which passes through a metal handle. The light ball is twirled and the centripetal force is provided by the weight of the heavy ball.
||Three balls, suspended by differing lengths of string from the same height on a rotating shaft, rotate in the same horizontal plane.
||Swing the Bucket
||Swing a bucket of water in a vertical circle and then in a horizontal circle over your head.
||A loop of chain is rotated very fast and then released onto the demo table, where it runs over obstacles while retaining its circular form.
||This demo uses an apparatus that rotates a ball on a string and that provides a means to cut the string while the ball is in flight.
Chapter7--Kinetic Energy and Work
||Weights of a proportion of 5-to-1 are the equilibrium conditions for this compound pulley.
||Double Pulley Setup
||A 500g mass balances a 1000g mass in a two pulley system; can show that the work done by each in moving is the same.
||Bosun's Chair -- Single Pulley
||Subject in harness with attached rope that flows through overhead pulley, pulls self up with a force equal to half subject's weight.
||Drive a nail into a block of wood with a pile driver.
||Spring Launched Cart on Level Track
||A spring (of measurable spring constant) launches a cart (with measurable final veloctiy) on a level air track. Mass of cart can be varied.
||Stretching a Spring
||Add masses to a spring and measure displacement; compare with a bungee cord.
Chapter8--Potential Energy and Conservation of Energy
||Bowling Ball Pendulum
||A bowling ball pendulum is pulled back until it touches the lecturer's nose and let go. The lecturer does not move.
||Galileo's Pendulum and Nail
||A pendulum started at the height of a reference line reaches the same height when its swing is intercepted by a post that effectively shortens the length of the pendulum.
||Loop the Loop
||A rolling ball must be released from a height equal to 2.7 times the radius of the loop.
||Spring-Launched Rolling Cart
||Predict the height to which a spring-compressed cart will rise on an inclined plane given the mass, spring constant, and amount of spring compression. Do the experiment.
Chapter9--Center of Mass and Linear Momentum
||Suspend a 2-dimensional shape from holes drilled near the edges, and use a plumb bob to find the center of gravity.
||Meter Stick on Fingers
||Slide fingers together under a meter stick to come together at center of mass. Repeat with mass attached to one end of stick.
||Throwing Foam Slab
||A slab of foam has its center of mass marked with a black dot; this dot follows a parabolic path when the slab is thrown.
||Air Track Inchworm
||Two air track gliders coupled by a spring will oscillate about the center of mass that is marked by a flag.
||Egg in sheet
||Throw an egg into a sheet held by two people.
||Spring apart Pasco carts
||Tripping the spring between two Pasco carts launches them in opposite directions; the cart masses may be varied.
||Compare a steel ball bouncing on an amorphous metal to one bouncing on stainless steel.
||Happy and Unhappy Balls
||Two black rubber balls of about 1.5 cm diameter are dropped from a height simultaneously. One ball bounces high while the other barely rebounds. Great to pass around.
||A toy rocket is launched twice, once when pumped up with air and once when pumped up with water.
||Five adjacent metal balls on a bifilar suspension illustrate momentum conservation properties.
||A tennis ball is placed on top of a basketball and both are released from rest.
||A long thin rid mounted perpendicular to a bar handle holds a 2 kg mass on a sliding collar.
||Movie: Milwaukee Pitstop Ad
||A humorous, fake video showing a car being rotating by a torque wrench. http://www.youtube.com/watch?v=q5LrarVz94g
||Equal Arm Balance
||Combinations of weights and distances on either side of the fulcrum of the equal arm balance may be selected to produce equilibrium. An oblique arm is used to show that the effective length of the lever arm is set by the component of the force.
||Students twirl equal mass wands, one with the mass concentrated in the middle, the other with the mass concentrated at the ends.
||Two equal masses with adjustable positions are mounted on a radial bar fixed to a horizontal axis with a pulley. A weight on a string rotates the assembly.
Chapter11--Rolling, Torque, and Angular Momentum
||Movie: Honda Cog
||Two-minute Honda movie ad of a series of mechanical cogs bumping into each other in sequence. http://www.youtube.com/watch?v=EEF0cg1j35
||Ring versus Disk Race
||The Matched Disk and Ring are identical in diameter and mass. When rolled down the inclined plane, the disk wins the race due to its lower moment of inertia.
||Two disks of identical mass, one weighted in the center and the othe weighted at the rum, are rolled down an incline.
||3 Cylinders of identical mass and appearance accelerate down an incline at different rates.
||Angular Momentum Vortx
||The angular speed of a quarter or steel ball increases as it rotates through ever-smaller circles down the Vortx.
||A balloon is attached to a Hero's engine-type arrangement of wings
||Collapse a spinning suspended Hoberman Sphere into a small ball.
||Bicycle Wheel Gyro
||The bike wheel is hung from its axle by a wire attached to the ceiling; when spun the bike wheel illustrates gyroscope motion nicely.
||This motorized gyroscope, used in the teaching labs, is good for showing a gyroscope's directional constancy; precession due to applied torques, and nutation.
Chapter12--Equilibrium and Elasticity
||Stable and Unstable Equilibria
||Two large rings each with two masses that have radially adjustable positions. Stable, unstable, and neutral equilibrium can be shown.
||Center of Gravity Blocks
||Stack blocks stairstep fashion at the edge of the table until the topmost block sticks out beyond the table edge.
||Tight Rope Walker
||The Tight Rope Walker consists of a pulley with four heavy lead weights on long semi-stiff wires symmetrically mounted around it. When placed on the "rope" (Cord), the weights hang down well under the rope, leaving the center of the Walker's mass below the rope and thus making it easy for the Walker to keep its balance.
||Tilted Pop Can
||A partially filled pop can when tilted appropriately will remain tilted
||The balancing bird is an example of stable equilibrium.
||Ladder against a Wall
||Set a ladder against the wall and walk up the rungs until the ladder begins to slide.
||Walking the Spool
||The spool can roll forward or backwards when the string is pulled, depending on the angle of pull.
||Suspend a wire from the ceiling and add masses until the wire breaks.
||A large fiberglass vortex-shaped cone is used to show circular and elliptical orbits and conservation of angular momentum.
||Satellite Launch Applet
||Animation launching a satellite tangentially to earth surface, as function of velocity: http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=24
||Press together two suction cups and try to pull them apart.
||Egg in a Bottle
||Put a lighted match inside a milk bottle and cover with a peeled hard-boiled egg.
||Water streams out from three holes at different heights in a tall cylinder.
||Tubes of different geometries rise vertically out of a common reservoir of colored water.
||Weigh Submerged Block
||A 2 kg Al cylinder, suspended from the 20 N spring scale, is lowered into water and the new weight is observed; Can have beaker on scale; Can lower into oil for comparison
||Finger in Water
||Ask what will happen when a finger is inserted into a beaker of water balanced on a pan balance.
||Ice Melting in Water
||Show that the water level doesn't change when the ice in a beaker of ice water melts.
||Coke and Diet Coke
|| An unopened diet soda can floats in water, and a regular soda can sinks.
||Two concentric cylinders, separated by corn syrup and with a line of dye in the syrup parallel to the axis, can be rotated and "unrotated" to restore the line of dye. [Broken]
||Air flows through a restricted glass tube to the atmosphere; the pressure at different points of the tube is shown by manometers.
||Funnel and Ball
||A ping-pong ball is supported by air streaming out of an upside down funnel.
||Fan blowing on Board
||A fan blows on a board mounted so that it can rotate about an axis in the wind. What orientation will the board take?
||Hold one of these cards horizontally in the air, and then drop one to observe the dominate behavior of the card orienting itself horizontally, as well as the slipping and rotating behavior believed due to turbulence.
||Blow up an 8-foot long bag with one breath.
||Ping Pong Ball and Racket
||Use a ping pong racket to hit a curve ball using a 2-3" diameter styrofoam ball or a ping pong ball.
||Spring and Weight
||A mass hangs on the end of a spring. Using two springs of different k and a variety of masses, show the effect of varying k and m.
||Springs in Series and Parallel
||A spring with mass m, two identical springs in parallel with mass 2m, and two identical springs in series with mass m/2 oscillate with the same period.
||Air track glider and Spring
||Two identical air track carts are attached to (opposite) ends of an air track by means of two different springs. A mass may be added to either cart, and the dependence of the oscillation frequency on mass and on spring constant may be explored.
||A steel cylinder is suspended by a steel music wire along its right axis. When the cylinder is displaced by rotation and released it will oscillate in simple harmonic motion.
||A bob on a string hanging from a stand exhibits simple harmonic motion for small angles.
||One pendulum four times longer than a second oscillates with twice the period of the second.
||Different mass pendula
||Three pendula of different masses but the same length all oscillate with the same period.
||Pendula Amplitude Dependence
||Two identical simple pendula set in motion with different initial amplitudes, oscillate nonisochronically.
||Shadow project a ball mounted on a rotating disk.
||Tacoma Narrows Film
||A 3 minute video of the collapse of the Tacoma Narrows Bridge. Very impressive and memorable.
||Damped Driven Hanging Mass
||A mass, supported by a spring whose support is driven, vibrates against a solid screen; the drive amplitude, frequency and the screen angle can be varied.
Chapter16--Waves -- I
||Pulse on 1.9m spring
||Give the 1.9 m spring a quick pulse. The length and/or tension in the spring can be varied. Good for showing pulses, standing waves, harmonics, energy transfer.
||Pulses on Torsional Wave Apparatus
||Excite each of the three torsional transverse wave machines by hand to show how the wave speed varies as the inertia of the medium (the rod length) varies.
||A long slinky is supported on a bifilar suspension, and the ends are taped to the lab stands, for showing longitutinal wave properties with minimal friction. [BROKEN]
||Two students stretch a slinky and send longitudinal waves down the slinky.
||Standing Waves on a String
||Use a mechanical vibrator to generate standing waves on a string with one end under tension from a hanging mass. Best under UV light
||Joined spring and cord
||The 1.9 m spring is attached to a rubber cord; pulses started at one end will produce both transmitted and reflected pulses.
||A driven Chladni plate covered with sand shows standing wave patterns. Noisy!
Chapter17--Waves -- II
||Range of Hearing
||Use a function generator and wide-range speaker to demonstrate the range of hearing.
||Speed of Sound by Phase Difference
||A function generator drives a speaker, and an oscilloscope displays the signals from the function generator and a microphone that moves radially from the speaker.
||Bell in a Vacuum
||An alarm buzzer is suspended inside an evaculated bell jar, turned on, and the bell jar is evaculated. When air is let back into the jar, the sound returns.
||Speaker and Candle
||A large speaker operating at low frequncy and large amplitude makes a candle flame oscillate.
||SF6 voice (or recorder)
||Fill your lungs with sulfer hexafluoride and then talk, sing, or blow a musical instrument.
||A closed-end, square wood organ pipe of adjustable length.
||Two Points in Ripple Tank
||Two point source generators of ripples show interference patterns in the ripple tank on the overhead projector.
||Moire Pattern Transparancies
||Transparancies with identical concentric circular patterns are placed on top of each other with a slight offset.
||A 2 meter long bar with a speaker at each end produces auditory interference patterns.
||Rub the edge of a goblet with a wet finger to make it sing. An oscilloscope can be used to measure the frequencies.
||Hanging weights on the end of a "guitar" can be varied to "tune" the guitar to a desired pitch.
||A long tube is rolled in front of a speaker driven by a sine wave generator to show resonance. A microphone probe shows pressure variations on the o-scope.
||Whirl a corrugated plastic tube to produce sound. At least five tones can be heard.
||Show nodes and antinodes with the flames coming from a row of holes in a hollow tube filled with propane.
||A student-class trombone illustrates the effect of pipe length on resonant frequencies.
||Beats with Tuning Forks
||Two tuning forks of identical frequency are mounted on resonant enclosures; when a small piece of wax is attached to one, beats can be heard.
||Swing a small battery powered buzzer on the end of a string in a circle over your head.
Chapter18--Temperature, Heat, and the First Law of Thermodynamics
||Gay-Lussac's Law--Constant Volume bulb
||The constant volume bulb is filled with helium at room temperature and pressure, then sealed. It is then immersed in boiling water, ice water, and liquid nitrogen (or in a alcohol/acetone bath).
||Egg in Milk Bottle
||A peeled, hardboiled egg is sucked into a milk bottle when the bottle is cooled, and comes out when the bottle is heated.
||Strips of dissimilar metals bonded together bend when heated. Makes a nice thermometer.
||Ball and Ring
||The Ball will pass through the hole in the brass plate (termed the ring) when both are at room temperature. When the ball is heated with the torch it expands and will not pass through the ring.
||Warmth from your hand forces liquid from the bottom to the top bulb.
||Metals Sinking into Wax
||Hot copper, lead, and aluminum cylinders at a common temperature are placed on a wax block.
||A small (2mm x 2mm) piece of tissue is put at the bottom of the "fire torch," a clear glass cylinder that is closed at one end. When a plunger is inserted into the open end and rapidly pressed inwards, the tissue bursts into flames.
||The pop-gun is an example of adiabatic compression
||One side of a glass tube loop is heated while a drop of ink is inserted in the other side.
||Melting Wax on Rods
||Three metal rods (Cu, Al, Steel), with wax mounted on the ends of each, radiate horizontally from a central heated disk. This is a race to see which melts first.
||Ice Melting Blocks
||A chunks of ice placed on an aluminum block melts much quicker than ice on a foam block.
||Light the Match
||A match at the focus of one parabolic mirrir is lit by a heating element at the focus of another parabolic mirror.
||Black and White Radiation
||A thermopile with indicator is held to both sides of a hot coffeepot with one side painted black and the other side white.
||Light shining on the "radiometer" makes the vanes spin, but in a direction opposite to that expected for light absorption and reflection.
||Project the spectrum of an incandescent bulb as a function of temperature.
Chapter19--The Kinetic Theory of Gases
||One Mole Bars
||Set containing one mole each of iron, copper, zinc, and aluminum.
||When one end of a glass tube with bulbs at each end containing water is placed in liquid nitrogen, the water at the other end starts to freeze.
||This toy bird keeps bobbing its head in water because the evaporative cooling and internal pressure differences force the liquid inside above its center of mass, whereupon it tips, momentarily restoring equilibrium.
Chapter20--Entropy and the Second Law of Thermodynamics
||An excellent, simple, working model of the Stirling engine.
Physics Lecture Demonstrations at
the Department of Physics and Astronomy
The Johns Hopkins University