The two $60$-$cm$-diameter cylinders in FIGURE $P14.39$, closed at one end, open at the other, are joined to form a single cylinder, then the air inside is removed.

A. How much force does the atmosphere exert on the flat end of each cylinder?

B. Suppose one cylinder is bolted to a sturdy ceiling. How many $100kg$football players would need to hang from the lower cylinder to pull the two cylinders apart?

A force is an external agent modifying a body's states of rest or motion. There is a magnitude and a direction to it. The force's direction is known as the force's direction, and the point where force is applied is known as the point where force is applied.

A spring balance is used to calculate the force. Newton is the $SI$unit of force $\left(N\right)$.

PREPARE:

Force does the atmosphere exert on the flat end of each cylinder

$F=PA$

Number of football players need to pull the two cylinders

$n=\frac{F}{mg}$

SOLVE:

(A)Force exerted on the flat end,$F=PA$

$=P\left({\mathrm{\pi r}}^2\right)$

$=\left(1.013\times {10}^{5}Pa\right)\times \pi {\left(30\times {10}^{-2}\mathrm{m}\right)}^2$

$=28.62\times {10}^{3}N$

$=2.9\times {10}^{4}N$

(B)Force exerted on the cylinder $F=nmg$,

Where $n$is the number of football players needed to pull the cylinders apart

$\therefore n=\frac{F}{mg}$

$=\frac{\left(28.62\times {10}^3\mathrm{N}\right)}{(100\mathrm{kg})\times \left(9.8\mathrm{m}/{\mathrm{s}}^2\right)}$

$=30$

ASSESS: Then that will take $30$football players, each weight $100$ kilograms, to separate two cylinders, which are really substantial.

$F=nmg$