Practise selecting instruments for mass, length, volume, angle and other variables, then reading their scales and reporting direct or derived values precisely.
A group of students uses pressurized air to move a piston that forces a nail into a block of wood. A gauge is used to measure the pressure P of compressed air above atmospheric pressure. The nail enters the wood perpendicular to its surface.
The students use a ruler to measure the length of the nail which remains above the surface of the wood as shown. The depth of the nail inside the wood is d. All necessary length measurements are recorded using a ruler with uncertainty .
Describe one consideration that must be made when placing the ruler to ensure that the length of the nail remaining above the surface of the wood is measured accurately.
The students systematically increase the pressure and calculate d.
Outline how the students determined the value of d.