Pressure (4.8-4.9)

Question 1

What is the equation for pressure?

Answer 1

Pressure(Pa / Kgm^-1s^-2) = Force(N / Kgms^-2) / Area(m^2)

Question 2

What is the equation for density?

Answer 2

Density(kgm^-3) = Mass(kg) / Volume(m^3)

Question 3

What is density?

Answer 3

Density is the mass per unit volume

Question 4

What is pressure?

Answer 4

Pressure is the normal force exerted per unit cross-sectional area

Question 5

What is the average pressure of the Earth’s atmosphere?

Answer 5

1.0 x 10^5 Pa

Question 6

How do you determine the density of an object?

Answer 6

To find the mass, you can put the object on a weighing scale. To find the volume of the object, you would partially fill up a measuring cylinder with water and then record the volume. Then, put the object in the measuring cylinder and record the new volume. After, find the difference in the volumes and that will be the objects volume. then put the mass and volume into the density equation.

Question 7

What is the equation for pressure in liquids?

Answer 7

Pressure(Pa / Kgm^-1s^-2) = height of the object(m) x density of liquid(Kgm^-3) x acceleration of free fall(ms^-2)

Question 8

How do you derive the equation for pressure in liquids?

Answer 8

Weight = mass x gravitational field strength
~Use the mass is density multiplied by volume (using the density formula)~
Weight = (Density x volume) x gravitational field strength
~Use the volume equation~
Weight = Density x (height x area) x gravitational field strength
~Weight is equal to pressure multiplied by area (using the pressure formula)~
Pressure = (Density x height x area x gravitational field strength)/ area
~The area’s cancel out~
Pressure = Density x height x gravitational field strength

Question 9

What is the equation for upthrust?

Answer 9

Upthrust(N / Kgms^-2) = Area(m^2) x X(height of object)(m) x Density(Kgm^-3) x gravitational field strength(N/Kg / ms^-2)

Question 10

How do you derive the upthrust equation?

Answer 10

Force at the top surface = depth(h) x density x gravitational field strength x Area
Force at the bottom surface = (depth(h) + height of object(X)) x density x gravitational field strength x Area
~Take away the force at the bottom surface from the force at the top surface~
resultant upward force = ((depth(h) + height(X)) x density x gravitational field strength x Area) - (depth(h) x density x gravitational field strength x Area) = Area x height x density x gravitational field strength
Upthrust = Area x height(X) x density x gravitational field strength