Bulldozer on Moving Sheet, 1E10.10 or 1C10.10

Topic and Concept:

1. Moving Reference Frames, 1E10. Relative Motion

2. Motion in One Dimension, 1C10. Velocity

pira200 Listed

Location:

• Cabinet: Mechanic (ME)

• Bay: (B4)

• Shelf: #2

Abstract:

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.

Important Setup Notes:

• The power switch is flaky and touchy

• Please remove the batteries after use to prevent corrosion.

Setup and Procedure:

1. Place sheet of paper or paperboard on table.
2. Turn on the bulldozer by flipping the switch to the left position or "forward" direction. (Note: Not all the way to the "left" works better. The switch is located at the rear of the bulldozer.)
3. Place the bulldozer on the sheet.
4. Pull or push the sheet to show subtractive and additive velocities, respectively.

Cautions, Warnings, or Safety Concerns:

• The 3 position switch was badly corroded years ago and is quite touchy.
• One may have to flip the switch back and forth several time to get the bulldozer to work.
• Don't move the switch all the way left or right, just far enough to make contact, about 2/3 the way over.

Discussion:

If the paper is moving in the same direction as the bulldozer, the velocity of the bulldozer relative to the audience/table will be the sum of the sheet and bulldozer velocities - simple vector addition. Likewise, if the sheet moves in the opposite direction as the bulldozer, the velocity of the bulldozer will be the difference of the two velocities - simple vector subtraction. One can have the bulldozer move diagonally across the sheet while the sheet is being moved. making use of a ceiling camera, the student will be able to see the relative motion better.

Videos:

• Lecture Demonstration's Youtube Channel

References:

• N/A

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