Chapter 3
3.1 Acceleration
Non-uniform motion – more complex
Velocity-Time Graph
Useful to make
 Consistent with position-time graph and
motion map
 Straight line versus curved line


Slope of line give acceleration
 Units m/s/s
 Rate of change of velocity
Graphs and Maps
x (m)
t (s)
v (m/s)
t(s)
Position-time and
velocity-time
Motion map
Acceleration
Vector quantity
 Avg a = Dv/Dt
 Change in velocity over a time interval is
average acceleration
 Change of velocity in an instant is
instantaneous acceleration

 Found by calculating slope of tangent at specific
time on velocity-time graph

When would average and instantaneous be
the same?
Motion maps

Show vectors on motion maps
Positive versus Negative
Assigning coordinate system is
important
 Deceleration is NOT a physics term

Kinematic curves

How are position-time, velocity-time and
acceleration-time graphs connected?
3.2 Constant Acceleration
 vf

= vi + aavgDt
df = di + vitf + ½ aavgtf2
 vf2
= vi2 + 2aavgDd
Graphs
Equations can be derived from
equations
 Displacement is area under velocity-time
graph

3.3 Free Fall

Motion of object when air resistance is
negligible and action considered due to
gravity alone

Rock versus feather falling in air on
earth
 On moon?
 On Jupiter?
Acceleration due to Gravity

All objects fall at
the same rate on
earth
 9.80 m/s/s

What does the
motion map for an
object falling look
like?
 x-t graph, v-t graph
Initial up, then down
Motion map
 x-t graph
 v-t graph
 a-t graph

Lab
Newton’s 2nd lab
 Freefall lab, ch 3, pg 76-77
