Table of Mechanics Mechanics (1A): Measurement Mechanics (1D): Motion in Two Dimensions Lecture Demonstrations

## Motion in One Dimension

PIRA classification 1C

22 Demonstrations listed of which 6 are grayed out.

 Grayed out demonstrations are not available or within our archive and are under consideration to be added.

# 1C05. Displacement

 PIRA # Demonstration Name Abstract 1C05.10 Stopping Motion Stopping the motion of a moving cart on a track with the use of strobe lights. (eye-blink stop motion)

# 1C10. Velocity

 PIRA # Demonstration Name Abstract 1C10.10 or 1E10.10 Bulldozer_on_Moving_Sheet A bulldozer powered by an electric motor moves in the same or opposite direction as the sheet which is moves beneath it to show Relative Motion in the content of addition and subtraction of velocities. 1C10.20 Constant Velocity - PASCO Dynamic Cart A PASCO cart on the PASCO track is given an initial velocity which should remain constant. Note: our PASCO setup has high friction so does not work as well as it should. See 1C10.27 for a better variation. 1C10.21 Block_of_Wood_on_a_String A wood block with attached string is pulled horizontally across a table at constant velocity in front of a meter stick. The time interval of the displacement can be measured using a stopwatch so that the velocity can be calculated. 1C10.25 Constant Velocity (Air Track & Glider) Dots are superimposed on the screen every half second to mark the position of the air glider. 1C10.27 Constant Velocity Glider on Air Track A glider on a level air track is pushed giving it a velocity which remains roughly constant on the low-friction surface. A timer together with a known displacement can be used to measure the velocity. 1C10.30 Approaching Instantaneous Velocity An air cart is given a reproducible velocity by a solenoid kicker. Flags of decreasing length interrupt a photo timer. 1C10.32 Strobed Disc Look at a fluorescent spot on a 1725rpm disc with a stroboscope at multiples of the frequency to demonstrate the limiting process. 1C10.40 A large steel ball accelerates down the inclined track and onto a flat track as a metronome ticks at constant time intervals. Analogous to 1C20.40 and sometimes used at the same time. 2C30.50 1C10.51 Terminal Velocity With Water, Glycerin, & Marbles Two identical marbles are dropped simultaneously into separate graduated cylinders, one filled with glycerine and the other with water. The marble dropped in glycerine will quickly reach terminal velocity, obtaining a slow and constant velocity that can be measured.

# 1C20. Uniform Acceleration

 PIRA # Demonstration Name Abstract 1C20.10 Penny and Cotton (AKA Guinea and Feather) Invert a large glass tube that contains a penny and a small cotton ball. Invert first with air and again when evacuated. 1C20.15 Drop Wooden and Lead Balls Show that the two balls, one substantially heavier than the other, when dropped simultaneously have the same acceleration and hit the ground at the same time. The two balls are the same size. 1C20.16 Ball, Paper, and Cotton Ball Drop A rubber ball, a cotton ball, a sheet of paper, and a crumpled sheet of paper are simultaneously dropped from the same height. Due to the different geometric profiles of each dropped object, the drag force on each will be different. 1C20.20 Equal Time & Equal Distance Two separate ropes strung through tennis balls are hung from the ceiling. On the first rope the tennis balls are spaced equidistantly (ex. every 3 feet). On the second rope the balls are spaced in a manner which represents the position of a falling ball at equal time intervals. (ex. every half second i.e. one ball at the top, one ball 4 ft below it, another 16 ft from the top, another 36 ft from the top, etc.) See Sutton M-84. 1C20.35 Inclined Air Track Using the PASCO interface, the echo censor and a computer to show the acceleration, velocity, or displacement graphs vs. time. The data is obtained from a cart on an inclined air track as it accelerates down and rebounds. (PASCO mass cars and track can also be used here.) 1C20.40 Aluminum Inclined Plane, Constant Acceleration A large steel ball accelerates down the inclined track as a metronome ticks at constant time intervals. Analogous to 1C10.40 and sometimes used at the same time. 1C20.50 Duff's Plane A ball leaves a trail as it oscillates back and forth while rolling down a chalk covered trough. See Sutton M-76. 1C20.60 A projectile is launched vertically from a risen platform relative to the ground. The projectile will reach a maximum height, stop, then fall the the ground reaching its greatest speed just before impact.

# 1C30. Measuring g

 PIRA # Demonstration Name Abstract 1C30.10 Free Fall Timer Drop a ball and time the fall. 1C30.16 Dropping Balls A ball is released by an electromagnet and a clock started. The catcher stops the clock, thus measuring the duration of the fall. 1C30.15 Free Fall Spark Apparatus A bob falls along a length spark tape to show the position of the bob at constant time intervals. 1C30.46 Video Strobe Water Drop Gravitometer Use the 60 Hz refresh rate of a video monitor to strobe falling drops by adjusting the rate to 60 Hz and having the stream fall past the screen. See TPT 28(2), 108. 1C30.55a Catch a Meter Stick, Reaction time Drop a meter stick and have a student catch it. Distance can be converted to reaction time. 1C30.55b Catch a Dollar, Reaction time Hold a dollar bill vertically and have the student put his thumb and index finger on either side of the bill at the midpoint. Drop the dollar and see that the student will likely not be able to react in the short time it takes for the dollar to fall through his fingers. See TPT 14(3), 177. 1C30.63 Pendulum Timed Free Fall A pendulum released from the side hits a ball dropped from the specific height that gives a fall time equal to a quarter period of the pendulum. See Sutton M-86. 1C30.66 Many Bounce Method Time a bouncing ball for many bounces and determine g using the coefficient of restitution. See AJP 55(1), 59.