(12) x vs. t just
600
becomes horizontal
here, like the top of
x
a hill. Must be
500
(11) Value of v is
horizontal here
[m]
decreasing meaning slope
since v = 0 at t = 20 s.
of x vs. t is decreasing meaning
it is “curved down”. Note that
400
values of v are still “+” so x is
increasing.
(8) Put point
here since 300
x = 225 m at
t = 0.
(10) v (below)
is increasing
(9) v is slope
200
meaning slope
of x vs. t, so, v
of x vs. t is
being constant
increasing
and “+” means
meaning
100
x vs. t is a
“curved up”
straight line
with “+” slope.
0 0
5
10
15
20
t [s]
35 m/s
v
35
(1) Put point
m
[ 30
s
]
here since
25
v = 15 m/s at
t = 0.
20
15 m/s
(3) Steady
15
increase in v
(2) Draw hori-
10
means straight
(4) Steady decrease
zontal line here
line from value
in v means straight
since v is con-
5
at 5
line from value at
s to value at
stant at 15 m/s.
10
10
s.
s to value at 20 s.
0 0
5
10
15
20
t [s]
4 m/s2
a
m
(6) a is slope of
[ ]
s2
v vs. t above;
v vs. t is straight
line with “+”
slope, so, a is
0
constant “+”
0
5 value meaning
10
15
20
t [s]
a vs. t is
(7) Above, v vs. t is a straight line with
(5) Constant v
horizontal.
“−“ slope, so, a is constant and “−“. When
means 0
a is constant, a vs. t is horizontal.
acceleration.
−3.5 m/s2
The key values on the v vs. t graph are givens so the only “mystery,” about the diagram above,
that remains is, “How were the key values on a vs. t obtained?” Here are the answers:
50