A- It is always a good idea to understand the \"size\" of units. The objects lis

Question

A- It is always a good idea to understand the "size" of units. The objects listed below are restiing on a hard surface. Categorize each object according to the pressure it exerts on the surface when placed on their side with the largest area, which is the bottom of each object is flat and that the pressure refers to that above atmospheric pressure (that is, gauge pressure).

The objects are: textbook, brick, can of soap, sheet of paper, penny.

The oressure: 0.01 Pa, 0.1 Pa, 1 Pa, 10 Pa, 100 Pa, 1000 Pa, 10000 Pa, 100000 Pa.

B- A news report states that a man was crushed to death in an industrial accident. According to the article, the pressure the man experienced was "nearly 1000 Pascals!". Based on this news report, what would you think about the veracity of their claims?

1- Impossible! A pressure like 1000 Pa is well beyond what a person can expect to ever experience.

2- The article sounds reasonable.

3- Ridiculous! A 1000 Pa pressure would not even hurt a person.

Explanation / Answer

A. Let us see.

P = Force/ Area. So,

textbook has a mass of say 1 kg, area of 30*30cm^2. Pressure = 100 Pa

brick mass = about same as textbook (In my country bricks are light, but might consider changing mass for your country :D)

= 100Pa

can of soap = 1 kg, 20 cm radius = 100 Pa

sheet of papaer = 2 grams, same area as textbook = 0.01 Pa

penny = 2.5g, 10mm = 10Pa

B.

Since the atospheric pressure is 101 KPa, or about 100000 Pa, that sounds ridiculos.

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