Category Archives: Applications of Newton’s Laws

Walking the Spool

Demo: ME-K-WS
Pira Index: 1K 10.30

 Lab Equipment  Directions
  1.  large cardboard spool with attached rope
  1.  Pull the rope at a slightly elevated angle and note the direction in which the spool rolls.
  2. Rewind the rope and pull it at a steeply elevated angle and note the direction in which the spool rolls.
  3. Pull at an angle somewhere between the first two and the spool will slide across the floor.
*At a shallow angle the spool rolls towards you – the center of mass is above the rope. At a steep angle the spool rolls away from you – the center of mass is below the rope.


Static vs. Kinetic Inclined Plane

Demo: ME-K-SK
Pira Index: 1K 20.37

 Lab Equipment  Directions
  1.  black metal inclined plane
  2. friction box with string
  3. 1kg hooked mass
  4. 2 – 500g slotted masses
  1.  Set the inclined plane to a 32 degree angle.
  2. Place the slotted weights in the box and place the string over the pulley. Hook the 1kg mass onto the end of the string. The masses will not move because of static friction.
  3. Tap the inclined plane to start the motion of the box up the ramp.
*Angle may need to be adjusted slightly to get the box to not slide until ramp is tapped.


Static Equilibrium Balls

Demo: ME-K-SE
Pira Index: 1K 20.00

 Lab Equipment  Directions
  1.  2″ steel ball
  2. super ball (slightly smaller than 2″)
The balls are supported against rolling, only if the upper has the greater product of mass and diameter.
  1.  Hold each ball separately in your hand and lean the hand so the fingertips are below the palm. Note how easily each ball rolls off as you increase the angle.
  2. Place the balls together on your palm as shown in step 3: superball above the steel. Note they still roll off easily.
  3. Now place the superball below the steel. Gradually tilt your hdand.


Hula Hoop

Demo: ME-K-HH
Pira Index: 1K 20.45

 Lab Equipment  Directions
  1.  hula hoop
  2. small piece of carpet
  1.  Throw the hoop out in front of you, giving it a backward spin. If it goes along the slick floor it takes some time to reverse its direction. If it hits a rug it reverses very quickly.


Frictional Starting Force

Demo: ME-K-FS
Pira Index: 1K 20.30

 Lab Equipment  Directions
  1.  special 4×4 block with hook
  2. 2 – 2000g pan balance masses
  3. 2000g dial spring scale
  4. special smooth – surface board (plastic coated surface)
  1.  Place the block on the long board and put the masses on the block.
  2. Attach the spring scale, pull very slowly, noting the maximum reading on the scale.
  3. Keep pulling the block at constant velocity and note that the scale reading is less than it the noted maximum to overcome static friction.


Feeble Minded Disk

Demo: ME-K-FM
Pira Index: 1K 10.50

 Lab Equipment  Directions
  1.  feeble minded disk
  2. inclined plane
  1.  Place the disk on a flat surface and release.
  2. The disk will roll in one direction, stop, and return.
  3. Place the disk at the bottom of the inclined plane with the lead plug toward the top of the plane.
  4. When released, the disk will roll uphill.
  5. To find the actual center of mass for the disk, suspend it from each of the three provided holes and draw a chalk line vertically downward from each hole.


Bed of Nails

Demo: ME-K-BN
Pira Index: 1K 30.10

 Lab Equipment  Directions
  1.  bed of nails (nails should be spaced evenly 1/2 inch apart)
  2. board approx. 8″ x 3′
  3. log (optional)
  4. towel or pillow to use as headrest
  1.  Place the small board on one end of the bed and sit on it.
  2. Carefully lay down on the bed.
  3. Remove small board.
  4. If desired, after subject is lying on the bed, you may add a heavy weight such as the log.
  5. To rise from the bed, replace the small board and help the subject up.


Action-Reaction Sprinkler

Demo: ME-K-AR
Pira Index: 1K 10.00

 Lab Equipment  Directions
  1.  rainbird sprinkler and connector
  2. vacuum cleaner/blower
  1.  Connect the hose between the blower and the sprinkler.
  2. Turn the vacuum/blower on and watch the sprinkler turn.


  1. Connect the hose to the vacuum end.
  2. Why doesn’t the force of the incoming air reverse the spin?