Pressure is the perpendicular force applied to the surface of an object per unit area over which that force is distributed.

A force is a push or a pull on an object. A force is an influence that can cause an object to change its speed.

Compound measures for pressure

Maths

Checking and further securing understanding of direct proportion in context

Compound measures for speed

Compound measures for density

Converting between metric speed measures

Converting between metric and imperial speed measures

Combining speeds

Combining densities

Problem solving with compound measures

In this unit, pupils will be exploring the multiplicative relationship between different compound measures. Ratio will be one of the ways in which this is explored and the skills from the prior unit will aid understanding. There are also links to the volume units as volume is required for the density formula.

In this unit, pupils explore the multiplicative relationship between different compound meaures and units such as speed, rates of pay, density and pressure.

Compound measures

Which of the following are units of pressure?

A box is placed on a table. The area of the base of the box is 1.25 m$$^2$$.  The force exerted by the box on the table is 38 N.  The pressure exerted by the box on the table is {{ }} N/m$$^2$$.

This box has a mass of 112 N.  Calculate the pressure it exerts on the ground.

The pressure exerted by a cube with side lengths of 5 cm on a table is 2.85 N/cm$$^2$$.  Find the force exerted by the cube on the table. 

This box exerts a pressure of 80 N/m$$^2$$ and a force of 76.8 N on the ground.  How wide is the box?  


The density of a substance is measured as the substance's {{ }} per unit of volume.

The volume of an object is 125 cm$$^3$$ and has a mass of 687.5 g. The density of the object is {{ }} g/cm$$^3$$

The density of an object is 15 g/cm$$^3$$, the mass of the object is 487.5 g.  The volume of the object is {{ }} cm$$^3$$

The density of an object is 5.6 g/cm$$^3$$, the volume of the object is 160 cm$$^3$$.  Calculate the mass of the object.  (Give your answer in grams)

The density of this cuboid is 1.8 g/cm$$^3$$.  Calculate the mass of the cuboid. 

Starter Quiz

The density of a substance is measured as the substance's per unit of volume.