Question

Which situation has the greatest pressure? A. Atmospheric pressure at sea level, equal to 1.01 X 105 N/m2 B. The pressure that a person of mass 70 kg exerts on the floor when she balances on the ball of one foot, with an area of contact of 50 cm2 C. The pressure that a physics textbook of mass 2.5 kg exerts on a desk when it is lying flat on the desk, with an area of contact of 22 cm X 28 cm

Answer 1

The correct option is B

Step-by-step explanation:

In part A pressure is given as
`1.01*10^5 N/m`

In Part B we can calculate the pressure using the formula

`P = (F)/(A)`

Where F is the force which in this case is weight which can be obtained as follow

W = Mg

Substituting 70kg for M and
`9.8m/s^2` for g

`W = 70 *9.8`

`=686N`

A is the area with a value
`50cm^2 = (50)/(10000) = 5.0*10^(-3)m^2`

So substituting into the above equation

`P = (686)/(5.0*10^(-3))`

`= 1.37 *10^5 N/m^2`

for part c

A
`= 22*28 cm^2= (22*28)/(10000)m^2`

`=6.16*10^(-2)m^2`

F
`= 2.5 * 9.8`

`= 24.525N`

Therefore
`P = (24.252)/(6.16*10^(-2))`

`= 298 N/m^2`

From this we see that the value of P for part B is the greatest