module 2

• A physical quantity is a property of an object that can be measured, with a unit

  
• Most quantities have a unit besides the magnitude/direction, given using the Système Internationale (SI) standard base units
• The seven SI base units can be derived by finding a formula for the quantity and substituting the units for each part of the formula
• To check the homogeneity of an equation, represent both sides in their SI base units and show they are equal
• Prefixes are used to represent quantities of extreme magnitude in physics, as abbreviations for numbers multiplied by a power of ten
• When creating graphs, label the axes with the quantity and unit, and ensure the graph covers over 75% of the space provided
• When calculating the gradient of a graph, draw a straight line of best fit and calculate using a triangle that covers at least 75% of the line
• Errors in measurements can be random or systematic, with random errors varying unpredictably and systematic errors differing from the true value by a consistent amount each time
• The accuracy of a measurement is how close it is to the true value, while precision is how close repeated measurements are to each other
• Uncertainty in a measurement is the interval in which the true value should lie, calculated using the range of measurements or the resolution of the measuring equipment
• When quantities are combined in an equation, the rules for calculating overall uncertainty vary based on how the quantities have been combined
• Anomalous data should be ignored when producing a graph for an experiment, and error bars are used to show the absolute uncertainty for each value
• When vectors are at angles to each other, a vector triangle is used to add or subtract them
• Vectors can be resolved into horizontal and vertical components using trigonometry