Standing on Light Bulbs

Standing on a light bulb

Difficulty: 8 out of a possible 10 advise that you explain it and not actually do it if your short on time!

Materials:

·        Triangular piece of wood designed with wires and inlets to allow 3 light bulbs to be screwed into the wood (equally apart).

·        An electrical cord allows the light bulbs to be plugged in.

·        The triangle is an equilateral triangle with sides of length 20 inches.

·        3 light bulbs (NOT fluorescent)

Procedure:

1.     The light bulbs are put into the piece of wood which is then turned upside down so that the wood is supported by the light bulbs

2.     The wires are connected to the light bulb and then the cord plugged into the outlet

3.     Once step two is done the light bulbs should turn on! (this adds a dramatic effect to the demonstration!)

4.     A demonstrator carefully places all their weight onto the piece of wood.

5.     If done correctly the light bulbs should be able to withstand the weight of the demonstrator.

Explanation:

The catenary shape of the light bulb allows it to withstand the force of gravity and weight that the demonstrator applies on it. Because of the reinforcing nature of this shape, it is very strong and can support much more weight than other round shapes. The exact physics behind the catenary are very complex, but the general idea is that each small portion of the shape is reinforcing the other portions.

Additional information:

Calculating the force applied on the light bulb:

Assume the demonstrators weight is 50 kg
Force of Gravity: 9.8

Fg= Force applied

Fg=ma

Fg= 50 X (9.8)

Fg= 490 N
Therefore the light bulbs are holding 490 Newton’s of force