Lesson video

Hi, my name is Mrs. Dennett and in this lesson we're going to be using and applying the pressure formula.

Let's start by thinking about what is pressure.

Well pressure is another example of a compound measurement.

It is the amount of force applied perpendicular that means that at right angles to a surface per unit of area.

So it's measured quite often in Newtons per centimetre squared.

So here we've got a measure of force, which is the Newtons and a measure of area centimetres squared or square centimetres.

So we're looking at measuring Newtons per square centimetre.

So the formula is calculated.

To find the pressure, we just divide the force by the area.

Units for density are always a unit of force in Newtons per unit of area.

And the unit of area can be centimetres squared metres squared, et cetera.

So let's have a look at a question where we need to apply the pressure formula.

So I've got the pressure formula there.

Force divided by area gives us the pressure.

And we're told that a force of 50 Newtons is applied to an area of 10 centimetres squared.

We want to work out the pressure.

So we've been given the force, which is 50 Newtons and the area, which is 10 centimetres squared.

So we put these into the formula and 50 divided by 10 is five and the units of measure will be Newtons per centimetre squared.

So the pressure is five Newtons per centimetre squared.

Let's have a look at a question where we have to work out the area of the surface using the pressure formula.

So we've got a force of 70 Newtons is applied to a surface.

The pressure exerted is 14 Newtons per metre squared.

So we've got the force, which is 70 Newtons and the pressure, which is 14 Newtons per metre squared.

So we put these values into our formula and we rearrange to calculate the area.

So the area will be 70 divided by 14.

So that's the force being divided by the pressure.

And we get an answer of five metres squared because the pressure exerted was in Newtons per metre squared, and we wanted the area and the measure of area is metres squared.

Let's have a look at a question where we might be required to work out the force.

So a pressure of 12.

5 Newtons per millimetre squared is exerted on an area of 16 millimetres squared.

So we've got the pressure which is 12.

5 Newtons per millimetre squared and we've got the area, which is 16 millimetres squared.

So we substitute these values into our formula.

And we have to rearrange our formula in order to find the force.

So we do 12.

5 multiplied by 16 which gives us a force of 200 Newtons.

Here are some questions for you to try.

Pause the video to complete the task and restart when you are finished.

Here are the answers.

The units for pressure are given by the unit of force in Newtons per area.

So we look for these units in the table.

For question two, we apply the pressure formula rearranging the formula for the last four rows as we're required to find the force or the area.

Here are some questions for you to try.

Pause the video to complete the task and restart when you are finished.

Here are the answers.

For question three, calculate 300 divided by 60 the force divided by area to get a pressure of five Newtons per centimetre squared.

For question four, work out force divided by pressure 44 divided by 28 which is 1.

6 metres squared to one decimal place.

That's all for this lesson.

Remember to take the exit quiz before you leave.

Thank you for watching.