- #1

Nirmal Padwal

- 41

- 2

- Homework Statement
- Suppose that, in a partial vacuum chamber having 3 molecules of air per cm##^3##, a cylindrical object of radius 10cm and length 40cm is to be moved in a straight line from point A to point B with its axis along the direction of motion. The distance bet4ween A and B is 50cm. How many molecules will hit the cylinder in its entire journey?

- Relevant Equations
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This is what I did, the cross-sectional area of the cylinder is ##\pi 10^2 = 100\pi## cm. Further, as the cylinder is moving a distance of 50cm. Thus, the total volume of vacuum, object covers throughout its journey is ##100\pi \times 50 =5000\pi## cm. Assuming that the molecules are uniformly distributed in the chamber, the number of molecules hitting the object is ##5000\pi \times 3 = 15000\pi \approx 47124## molecules.

Is this solution correct? I was confused because if it were, why was the length of the object given?

Is this solution correct? I was confused because if it were, why was the length of the object given?