Wooden Slat & Boston Globe
A stiff wooden slat is placed on a table so that 3 or 4 inches hang over the edge. The slat is covered by a single sheet of the Boston Globe. If the exposed end of the slat is struck sharply downward, what will happen?
a. Although the newspaper will barely ripple, the slat will break.
b. The newspaper will rip down the middle.
c. The newspaper will be propelled about five feet about the table.
d. The newspaper and slat will both fly off the table in opposite directions.
Materials
Wooden Slat: 0.22 x 1.35 x 18 inches (white pine)
Boston Globe: two unfolded sheets
Comments
A spectacular demonstration of Newton's First and Second Laws of Motion and the surprisingly large force that air pressure can exert on an area the size of an unfolded newspaper sheet.
Dimensions of Globe Sheet:
|
W
|
L
|
Area
|
|
25
in
|
22
in
|
=550 in2 |
|
63.5
cm
|
55.9
cm
|
=3549cm2
|
Force of
Air Pressure on Globe Sheet:
|
15
lbs/in2
|
x
|
550in2 |
=8,250 lbs |
|
10.35
N/cm2
|
x
|
3549 cm2 |
=36,712
Newtons
|
Notes
1. Table edge should be sharp.
2. Wear a glove to protect your hand.
3. 1 lbs = 4.45 Newtons
- Ernest Goldberg, RE-SEED Volunteer, Groton-Dunstable Middle School, 978-692-4281