Main Kinematical Quantities
- Displacement:
 x = x2 – x1;
Difference between this and distance traveled, d.
- Speed and velocity: The rate at which position changes in
time,
average speed = d / t,
a scalar; average
velocity = x / t,
a vector;
instantaneous velocity v = limit of x / t when t is
very small .
- Acceleration. The rate at which velocity (not speed) changes
in time,
average acceleration = v / t ;
instantaneous acceleration a = limit of v / t when t is
very small .
- Graphs: Be able to draw and interpret graphs of displacement, velocity
and acceleration versus time for various kinds of motion.
Motion with Constant Acceleration
- Main equations: If at some initial time the object is at x0
moving with velocity v0,
and for a time interval t it accelerates with acceleration
a, then the average velocity is (v + v0)/2
and
v = v0 + at
x = x0 + v0t + at2/2
v2 = v20 +
2a(x–x0)
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- Falling objects: Neglecting air resistance, the acceleration
is constant and directed downwards, with magnitude g =
9.80 m/s2.
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