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Can a toilet-paper tube support your weight?
Columns are often used to hold up heavy loads, such as the roofs of buildings. The heavy load pushes on the column, putting it in compression. So, a good column should be very strong in compression.

What You Need
• 2 empty toilet-paper tubes
• sand or salt
• dishpan, tray, or cardboard box lid
• sturdy chair
• funnel

Make a Prediction
Predict whether a toilet-paper tube can withstand the compression caused by your weight. Explain the reason for your prediction.

Try It Out
1. Place an empty dishpan, tray, or box lid on the floor. Stand an empty toilet-paper tube (the column) on one end in the pan.
2. While holding on to the back of the chair with both hands, gradually press straight down on the top of the column with one foot. Continue increasing your weight on the column until it collapses. Use this scale to rate the column's strength:

 1 Very weak! It crumples or breaks with hardly any force. 2 Only fair—it canít withstand much force. 3 Pretty good—it takes a lot of force to break it. 4 Super strong! We can't break it.

3. Observe the collapsed tube to see where it failed. How can you make the column stronger, using only tape and sand? Repeat Step 2 using the second toilet-paper tube and your new design.

Explain It
How did the strength ratings for the two columns compare? Explain what you think accounted for any difference. Were you surprised by the results of this activity? Why or why not?

Build on It
Is there any difference in strength between a column filled with small particles, like sand or salt, and a column filled with big particles, like marbles or pebbles? Make a prediction and test it.

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