# Physics Lecture Demonstrations

## Part I Chapters 1-15

Compiled November 5, 1999

### Chapter 1: Preludes

M-a1a Meter Standard A replica of the platinum-iridium bar in Paris that was the international standard for length before 1960. Video Camera needed for auditorium use.
M-a6a Powers of Ten "Powers of Ten" is a 9 minute film spanning scales from the edge of the universe to the sub-atomic.

### Chapter 2: A Mathematical Toolbox

M-c1a Tank on moving sheet A battery powered tank runs at constant speed on a moving paper to show how velocities add and subtract.

### Chapter 3: Rectilinear Motion

M-c1b Linear Air Track: Position vs. Time A glider glides down the 5 m air track while evenly spaced photogates record the elapsed time.
M-c4a Motion Detector and Student A student walks back and forth in front of an ultrasonic motion detector, and a real-time graph of the displacement (and/or veloctiy and/or acceleration) versus time is projected on the screen.
M-c3a Timed Free Fall A metal ball is dropped from first 1m, then from 4m into a catch bucket. A precise digital timer records the amount of time needed to fall those respective distances.
M-c2a Dime and Feather Tube A penny and a feather fall freely inside a glass cylinder that can be evacuated.

### Chapter 4: Kinematics II: Motion in Two and Three Dimensions

M-d6e 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. Have auditorium and classroom versions.
M-d6d Balls Shot and Dropped A ball is dropped and simultaneously another is projected horizontally; they hit the floor at the same time. Very visible
M-d6c Jumping Block -- Wheeled Cart A ball projected vertically upward from a moving air track glider falls back into the muzzle. (UNDER REPAIR)
M-d6g Range of a Gun Shoot at 45, then calculate 30 or 60 and place the target.
M-c1a Tank on moving sheet A battery powered tank runs at constant speed on a moving paper to show how velocities add and subtract.
M-d5a Orbit Ball 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.
M-d1f 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.

### Chapter 5: Newton's Laws of Motion

M-f2a Inertia Masses 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.
M-f2b Hammered Blocks The bottommost of a stack of blocks, when struck sharply, will slide to the side while the upper blocks remain in place.
M-f3a Glider on Level Air Track A glider on a level air track persists in gliding.
M-g1d Fan Propelled Cart Measure the final speed of a fan-propelled (constant acceleration) cart whose mass can be varied.
M-h1c 3rd Law with Scales Pull on two coupled spring scales with springs of equal or unequal strength.
M-j3a Suspended 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.
M-m2a Simple Pulley Show a simple pulley in equilibrium
M-j3c Rope and Three Students Two large strong students pull on the ends of a rope and a small student pushes down in the middle.
M-g1c Atwood's Machine Two equal masses are hung from a pulley. A small amount of mass is transferred from one side to the other.
M-k2a Friction Cars The forces required to move teflon-coated, rubber-coated, and wooden surfaced carts are displayed on a spring scale.
M-k2b Static vs. Sliding Friction Use a spring scale and block on the inclined plane to show that static friction is greater than sliding friction.
M-k2c Friction Block on Inclined Plane The Plane Surface is raised to an inclination of 10 to 1 by the lab stands. Weights are then selected to place the car (with varying loads) in equilibrium.
F-c3c 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

### Chapter 6: The Gravitational Force and the Gravitational Field

M-L2a Gravitational Well A large fiberglass vortex-shaped cone is used to show circular and elliptical orbits and conservation of angular momentum.
M-xxx Cavendish Balance Videodisk The Cavendish Balance is on videodisk.

### Chapter 7: Hooke's Force Law and Simple Harmonic Motion

W-a2c 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.
W-a2a 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.
W-a1a Simple Pendulum A bob on a string hanging from a stand exhibits simple harmonic motion for small angles.
W-a1b 4-to-1 Pendula One pendulum four times longer than a second oscillates with twice the period of the second.
W-a1c Different mass Pendula Three pendula of different masses but the same length all oscillate with the same period.
W-a6c 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 (damping) can be varied.
W-a6a Tacoma Narrows Film A 4.40 minute video of the collapse of the Tacoma Narrows Bridge. Very impressive and memorable.

### Chapter 8: Work, Energy, and the CWE Theorem

M-m2c 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.
M-m4a 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.
M-m4b Galileo's Pendulum and Nail Intercept the swing of a pendulum by a post at the bottom of the swing; the ball rises to the same height independent of the length of the pendulum.
M-m4f Spring-Launched Rolling Cart Predict the height to which a spring-compressed glider with rise on an inclined air track given the mass, spring constant, and amount of spring compression. Do the experiment.
W-a2b Spring and Air Cart An air track glider is attached to a horizontal spring and displaced from equilibrium.
M-m3a Decelerated Pendulum Rider A pendulum hits a level board, transferring a mass rider that slides to a stop.

### Chapter 9: Impulse, Momentum, and Collisions

M-n1b Egg in Sheet Throw an egg into a sheet held by two people.
M-n2a Fire extinguisher wagon Mount a fire extinguisher on a cart and take a ride. [Up to one week's notice required for extinguisher.]
M-n2b Water Rocket A toy rocket is launched twice, once when pumped up with air and once when pumped up with water.
M-n3c Elastic Collisions on Air Track Elastic collisions between air track gliders of equal and/or unequal mass.
M-n3d Inelastic Collisions on Air Track Inelastic collisions between air track gliders of equal and/or unequal mass.
M-n3a Newton's Cradle Five adjacent metal balls on a bifilar suspension illustrate momentum conservation properties.
M-r4a 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.
M-r4b Atomic Trampoline Compare a steel ball bouncing on an amorphous metal to one bouncing on stainless steel.
M-h1b Tennis Ball Cannon A cannon mounted on the air track shoots a tennis ball out horizontally.
M-j1a Determining Center of Mass Suspend a 2-dimensional shape from holes drilled near the edges, and use a plumb bob to find the center of gravity.
M-d4b Motion of an Extended Object 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.
M-d4e Air Track Inchworm Two air track gliders coupled by a spring will oscillate about the center of mass that is marked by a flag.
M-j1c Center of Gravity Blocks Stack blocks stairstep fashion at the edge of the table until the topmost block sticks out beyond the table edge.

### Chapter 10: Spin and Orbital Motion

M-xxx Round Platform with balls that rotate A round platform with two wooden balls attached (a third can be placed in the middle) is mounted to a variable speed motor. Illustrates both spin and rotational motion. NEW
M-j4e Torque Bar A long thin rid mounted perpendicular to a bar handle holds a 2 kg mass on a sliding collar.
M-q2a Whirlybird 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.
M-xxx Wrench, Nut, and Bolt Use a wrench, nut, and bolt to illustrate torque. NEW
M-d5a Orbit Ball 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.
M-q1a Inertia Wands Students twirl equal mass wands, one with the mass concentrated in the middle, the other with the mass concentrated at the ends.
M-xxx Toy Top A toy top, if we have one.
M-q5d MITAC Gyroscope This motorized gyroscope, used in the teaching labs, is good for showing a gyroscope's directional constancy; can also show precession due to applied torques.
M-q1b 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.
M-q1c Racing Disks Two disks of identical mass, one weighted in the center and the othe weighted at the rum, are rolled down an incline.
M-q1d Racing cylinders The Set of 3 Cylinders appear to be identical and they have the same mass, but internally, the mass is distributed differently and they accelerate at different rates down an incline.
M-m4c Loop the Loop A rolling ball must be released from a height equal to 2.7 times the radius of the loop.
M-q6a Good, Bad, and Giant YoYos Comparison betwen well and poorly designed yoyos.
M-q4a Rotating Platform and Weights Spin on a rotating platform with a dumbbell in each hand.
M-q4b Swinging Bat on Rotating Platform Stand on a rotating platform initially at rest, and swing a bat or a mallet.
M-q4c Bike wheel on rotating platform Invert a spinning bicycle wheel while standing on a rotating platform.
M-q5c 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. [Ceiling hooks are in Auditorium and Rm. 278]
M-j4c Equilibrium of Forces I A horizontal beam with a sliding 1 kg mass is hung between two spring scales.
M-j4b 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.
M-j2b 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.

### Chapter 11: Solids and Fluids

M-r2b Young's Modulus Suspend a wire from the ceiling; using a ruler next to a mark on the wire, hang weights and measure the change in position. Knowing the length, cross sectional area, and the change and length, Young's modulus can be calculated.
M-r2a Breaking Wire Suspend a wire from the ceiling and add masses until the wire breaks.
M-r3a Deformation of Solids The large book can be pushed perpendicular to the spine to show shear.
F-b2a Pascal's Vases Tubes of different geometries rise vertically out of a common reservoir of colored water.
F-b3a Crush the Can A vacuum pump evacuates a 1 gallon can; atmospheric pressure crushs the can.
F-b3b Magdeburg Disks Evacuate Magdeburg hemispheres and try to separate them.
F-b2f Hydraulic Press Break a piece of wood in a hydraulic press.
F-b4a 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 also lower into oil for comparison.
F-a1a Floating Metals Float a razor blade, a paperclip, and a needle on the surface of water.
F-c2a Bernoulli Tubes Air flows through a restricted glass tube to the atmosphere; the pressure at different points of the tube is shown by manometers.
F-c2b Floating Ping Pong Ball A ping pong ball floats in an upward stream of air.
F-c2c Funnel and Ball A ping-pong ball is supported by air streaming out of an upside down funnel.
F-c2d Windbag Blow up an 8-foot long bag with one breath.
F-c2e 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.

### Chapter 12: Waves

W-b1a 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. Better than rope!
W-b2a Hanging Slinky 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. [Under development.]
W-d2a Guitar Hanging weights on the end of a "guitar" can be varied to "tune" the guitar to a desired pitch.
W-b1b Pulse Propagation (Inertia) 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.
W-b1c Shive's Reflection at a barrier Send pulses down a Shive wave model machine with the other end free, then fixed.
W-b2k 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.
W-b3a 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.
W-b4a Doppler Buzzer Swing a small battery powered buzzer on the end of a string in a circle over your head.
O-c1a Single Slit Diffraction Pattern Shine a laser beam through single slits of various widths.
W-d2a Guitar Hanging weights on the end of a "guitar" can be varied to "tune" the guitar to a desired pitch.
W-d3a Resonant Tube A long tube is rolled in from of a speaker driven by a sine wave generator to show resonance. A microphone probe shows pressure variations on the o-scope.
W-d4a Beats 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.
W-c5a Pasco Fourier Synthesizer Construct, hear, and see waveforms built from the 440 Hz fundamental and up to eight harmonics.

### Chapter 13: Temperature, Heat Transfer, and the First Law of Thermodynamics

H-e3a 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).
H-a3a Bimetallic Strip Strips of dissimilar metals bonded together bend when heated. Makes a nice thermometer.
H-a3b 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.
H-b1a Equipartition Theorem The heat capacity of a 1 kg steel mass is measured by calorimetry.
H-b1b Metals Sinking into Wax Hot copper, lead, and aluminum cylinders at a common temperature are placed on a wax block.
H-b2a Convection Tube One side of a glass tube loop is heated while a drop of ink is inserted in the other side.
H-b3a 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.
H-b4b Light the Match A match at the focus of one parabolic mirror is lit by a heating element at the focus of another parabolic mirror. [Delicate Demo]

### Chapter 14: Kinetic Theory

H-d1a Brownian Motion The Brownian movement of smoke particles in air is projected onto a screen or wall for all to see.
H-d2a Crookes' radiometer Light shining on the "radiometer" makes the vanes spin, but in a direction opposite to that expected for light absorption and reflection.
H-b7a Fire Syringe 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.
H-b7b Temperature Increase Generated by Pressure A thermocouple embedded in a cylinder-and-piston assembly causes a galvanometer deflection when the cylinder is pressurized.

### Chapter 15: The Second Law of Thermodynamics

H-f3a Stirling Engine An excellent, simple, working model of the Stirling engine.