Tuesday, February 25, 2014

The Slipping Ladder: Exploring Ladder Heights (Angles) and a Lubricant

Continuing on our slippery themed activities {here, here and here}, we explored when a ladder will slip and fall to the ground.  We, as adults, consider the angle of the ladder when tackling a project, furthermore we take into account the properties of the ground.  One may feel more comfortable with a ladder at a certain angle on rocks compared to on pine needles.

To help our little ones develop this intuition we setup the ladder activity.  The goal of this activity is to adjust the angle of the ladder to determine when the angle that the ladder will fall.  We then changed the surface of the "ground" and repeated the activity to explore if that angle/height changed.



We leaned a ladder (designed for pet birds) against a wooden box.  We began when the ladder was at 90 degrees or straight up and marked the level of the top rung on the box.


We then moved the ladder down a little bit (resulting in a smaller angle with the ground).  It did not slip and fall so we marked this level on the box as well.



We continued until the ladder could not stay up against the box and slipped and fell.

Now the fun started!  We put a small amount of dishsoap on the foil and poured a bit of water and spread it all around.  The whole surface was nice and slippery.  We spoke about how the surface felt and what we thought might happen to the ladder this time around.



We put the ladder back vertically against the box and repeated the steps trying to match the levels of the ladder before.



This time the ladder slipped at a higher location (larger angle) than before.  The slippery surface had reduced the friction and resulted in the ladder slipping at a higher height.



We hope you enjoy this activity. There are so many ways to expand up on it: putting different lubricants on the surface, making the surface sticky, putting sand or pineneedles on the ground.  You could also have an older child measure the angles with a protractor or calculate the angle after measuring the height.  One more fun idea would be to put a weight (like a person) at the top and see if that makes a difference as well.

Enjoy!

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Supplies:
  • foil
  • detergent
  • water
  • ladder (or equivalent)
  • paper to mark the heights of the ladder
  • tape to stick down the foil
  • markers 
Instructions:
  1. Place paper for marking the height of the ladder on the wall or on a box.
  2. Tape the foil down in front of it.
  3. Stand the ladder vertically against the paper and mark the height of the top rung.
  4. Move the ladder out at the bottom marking the height each time until the ladder slips and falls down.
  5. Cover your foil with soapy water (mix a small amount of dishsoap with a tablespoon of water and spread over the surface.
  6. Repeat step 3 and 4 until the ladder falls.
  7. Note if the last recorded height was above or below the un-lubricated surface.
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