Category Archives: Work and Energy

Tail Wags Dog

Demo: ME-M-TW
Pira Index: 1M 40.57

 Lab Equipment  Directions
  1.  special watch with attached mirror
  2. low friction pivot
  3. small plastic box with rubber feet on top
  4. laser pointer
  1.  Balanced the watch face down on the pivot.
  2. Place the laser on top of the box with the rubber feet on the box elevating the laser slightly to align it with the mirror on the side of the watch.
  3. Look for the reflected light on a distant wall. Observe the motion of the dot on the wall.


Track, Loop the Loop

Demo: ME-M-TL
Pira Index: 1M 40.20

 Lab Equipment  Directions
  1.  loop the loop track (large)
  2. metal ball
  1.  Place the ball at the highest point of the long end of the track.
  2. Release the ball and observe.
  3. The angle of the track may be changed by tilting in order to demonstrate that less potential energy means less kinetic energy.


Track, Conservation of Energy

Demo: ME-M-TC
Pira Index: 1M 40.30

 Lab Equipment  Directions
  1.  conservation of energy track
  2. metal ball
  3. teflon ball
  1.  Place the ball at the highest point of the shallow angle and release.
  2. Note that the ball goes to the same height as the release height.
  3. Repeat this from the other end.
  4. Repeat steps 2 and 3 with the other ball.


Stopped Pendulum

Demo: ME-M-SP
Pira Index: 1M 40.15

 Lab Equipment  Directions
New set up:

  1. Plexiglass and 2 rod pendulum set up
Old set up:
  1. lab stand (short)
  2. right angle clamp
  3. short metal rod
  4. pendulum clamp
  5. steel ball
  6. string
New – Hand out apparatus as shown.

If they prefer old demo:

  1. Attach pendulum clamp at top of stand and crossbar, about 3/4 of the way down.
  2. Determine correct length of string by wrapping ball once around crossbar and then attaching to pendulum clamp.
  3. Unwrap ball from crossbar and drawing it back, release it from progressively greater heights until it wraps around crossbar.


Projectile Launcher

Demo: ME-M-PR
Pira Index: 1M 40.65

 Lab Equipment  Directions
  1.  Pasco projectile launcher
  2. plunger
  3. plastic balls
  4. small C-clamp
  1.  Clamp the launcher to table. Using the plunger, push ball in to short range setting. Point the launcher straight up and fire. Measure the height.
  2. Turn the launcher to horizontal and fire again from the short range. Use the height and range of this ball to determine initial velocity. (t=2y/g and vo=x/t)
  3. Using conservation of energy calculate the maximum height of a vertical shot. Compare with the value from #1.
  4. Set the launcher to various angles to find the angle which gives maximum range.


Pendulum Lift

Demo: ME-M-PL
Pira Index: 1M 40.12

 Lab Equipment  Directions
  1.  two lab stands
  2. two pulleys on rod
  3. three 90 degree clamps
  4. three C-clamps
  5. lab jack
  6. balance auxiliary masses (1000g)
  7. balance auxiliary mass (500g)
  8. copper string guard
  9. string
  10. postal balance
  1.  Set up as shown.
  2. Pull the smaller weight to one side creating an angle with the string guard. As it swings, note that the other weight is lifted slightly causing the scale reading to roll back and forth.
  3. Test the lifting power at different angles of swing.


Pile Driver, PVC

Demo: ME-M-PD
Pira Index: 1M 10.20

 Lab Equipment  Directions
  1.  large drop tube (PVC and acrylic)
  2. release pin
  3. small acrylic drop tube
  4. steel cylinder (2″ x 6″)
  5. wood block 2″ x 6″ x 13″
  6. bag with nails
  1.  Place wood block on its side and put a nail into the wood just enough to make the nail stand up.
  2. Drop cylinder through the short tube counting, the number of drops it takes to drive the nail in.
  3. Set up another nail under large tube and drop cylinder (from what is equivalent to 3 times the height of the original tubing) again counting the number of drops needed to drive it in.
Release pin is used to poke into the holes in the PVC pipe to hold the steel cylinder at various heights. Put the pin to allow it to drop.


Pendulum, Bowling Ball

Demo: ME-M-PB
Pira Index: 1M 40.10

 Lab Equipment  Directions
  1.  bowling ball with attached rope
  1.  Set up the demonstration by hanging the bowling ball securely from overhead support.
  2. Pull ball back in an arc until it is just in front of your nose (stand with your back against something so that you do not lean forward at all).
  3. Release the ball with zero velocity (DON’T push).
  4. Remain still as ball returns. It returns to a point just short of where it started.


Pulley Advantage

Demo: ME-M-PA
Pira Index: 1M 20.10

 Lab Equipment  Directions
  1.  one movable pulley
  2. 20N scale
  3. two lab poles
  4. two telescope clamps
  5. three 90 degree clamps
  6. two 2000g masses
  7. one long string (for pulley) and one short string for direct mass attachment
  1.  Hang a string from the scale and attach a 2000g mass at the end of the short string. Note the scale reading of about 20N.
  2. Attach the long strip to the scale, through the pulley, and to the clamp on the upper lab pole. Now attach the 2000g mass to the movable pulley. Note the scale reading indicates the force to be about 1/2 of the force needed to lift the mass.


Maxwell’s Wheel

Demo: ME-M-MW
Pira Index: 1M 40.50

 Lab Equipment  Directions
  1.  Maxwell’s wheel apparatus
  2. 90 degree clamp
  3. hook clamp
  4. lab stand
  1.  Set the apparatus up as shown with the wheel being rolled up on its strings and supported in place by the hook clamp.
  2. Loosen the hook clamp allowing the wheel to fall. The motion will continue up and down for three or four minutes.