Introduction to Physics
The Study of Motion
Physics is the attempt to explain the interaction of matter and energy. How matter behaves when energy acts upon
it. Physics uses models, mathematical relations & language in an attempt to explain matter energy interactions and make predictions
involving these interactions.
In order for matter to "move" energy must be applied to it. In this strand we wish to study how matter or an object will "move" once it has
been caused to be in motion. We will not be concerned with the energy itself. Energy and the forces it generates is studied in grade 11.
What Can be Measured.
- distance; the linear distance between two points
- time; how long does it take for an event to occur. If there is no motion there probably is "no time".
- temperature: a measure of the average kinetic energy of the substance's molecules
- mass; the amount of material in a piece of matter
- electrical quantities like voltage, current and resistance
These are the major quantities of measurement
A list of other quantities to be studied later in a physics program.
- radiation frequencies; how do you think you tune your radio or TV
- magnetic field strength
- light intensity
- sound intensity and pitch
- gas pressure
- there are others but that's enough
You should know the various gadgets or devices that are used to measure the quantities found in the first list.
All other quantities that you encounter to be measured are just combinations of the above and I will call them composite measurments.
For example, density . There is NO gadget that directly measures density. To determine the density of a material you must mass
the object then find its volume. Afterwards you apply a formula to obtain the density. Volume, if its a liquid you could use a graduated
cylinder, however volume in actual fact is the product of length x width x height. These are three distance measurements multiplided
together.
Making Measurements and Calculations
Your text book (pages 344 to 346) covers these topics more than adequetely. Make sure you listen for explinations with examples
done in class.
Motion
These are two aspects investigated when studying motion:
Kinematics The motion of bodies without reference to the forces acting upon the body and
Dynamics The motion of bodies with consideration of the forces acting on the body which leads to Newtonian physics
and is studied in grade 11.
We, of course, will be studying kinematics with emphasis on motion in a straight line (Curvilinear motion is beyond your
mathematical scope).
The quantitative aspects of motion depend on
- position of the body being observed
- distance travelled and its corresponding displacement
- time it takes to transverse the given distance
- speed or velocity of the object in motion
- any accelerations that may occur
The simplest study of motion involves an object, moving, in which the changing distance is measured to the corresponding time it takes
for that change to occur. This is what speed is.
When doing speed studies a distance transversed by an object in a fixed amount of time will be mathematically considered an
ordered pair and as such may be graphed in two dimensions. Tabulating data of this nature will enable you to make
predictions of the objects motion. This is the whole purpose of kinematics. For example; how long will it take you to get to school in
the morning if your distance to school is 2.3 km and your ride travels at 50.0 km/h ?
Three terms to describe speed and each one is a little different from the other
- average speed
- instananeous speed
- constant speed
Each of these will be studied (page 254 & 255 in text book)
In doing experimental speed studies you will have to make accurate measurement of distance and time.
The data collected will be tabulated in a proper chart for subsequent graphing and analysis.