Question

An airtight box, having a lid of area 80.0 cm^2, is partially evacuated. Atmospheric pressure is 1.01 Times 10^5 Pa. A force of 108 lb is required to pull the lid off the box. The pressure in the box was:_________.

Answer 1

5×10^4Pa

Step-by-step explanation:

Given force of 108 lb is required to pull the lid off the box,

To convert "Ib"to Newton ,we use conversation rate below

1 pounds = 4.4482216282509 newtons

Then 108 lb=x Newton

Cross multiply we have

X= 480.41Newton

The force that is needed to open the lid is F and pressure P.

We know that Pressure= Force/Area

Area is given as 80.0 cm^2, we can convert to m^2 for unit consistency since 1cm^2= 0.001m^2 then

80.0 cm^2 = 80×10^-4m^2

Substitute to the equation of the pressure we have

P= 480.41Newton/(80×10^4m^2)

P=6×10^4 Pa

The pressure in the box will be difference between the initial pressure and final pressure

=( 1.01 ×10^5 Pa)-(6×10^4 Pa)

= 50100Pa

= 5×10^4Pa

Therefore, The pressure in the box was

5×10^4Pa