### Freefall-Intro

```y0 = 0 m
+y
5m
10 m
15 m
20 m
25 m
30 m
35 m
40 m
45 m
a = +9.8 m/s2
Free fall acceleration
is always
Find
v
and
y at t = 1 s
v
=
0
m/s
V = 9.8 m/s
0
down, if down is positive then so is
2
acceleration,
if
up
is
positive,
then
v = v0 + at = 0 + 9.8m s ×1s = 9.8m
acceleration is negative
y =?
9.8m????
s
NO!
Coyote was not going 9.8 m/s during the entire
first second, use average velocity
v0 + v 0 + 9.8m s
v=
=
= 4.9 m s
2
2
y - y0
v=
t
y = vt + y0 = 4.9m s ×1s + 0 = 4.9m
+y
5m
10 m
15 m
20 m
25 m
30 m
V = 9.8 m/s
40 m
45 m
a = 9.8 m/s2
v0 = 0 m/s
Find v and y at t = 2 s
v = v0 + at = 0 + 9.8m s × 2s =19.6 m s
2
v0 + v 0 +19.6 m s
v=
=
= 9.8m s
2
2
V = 19.6 m/s
y - y0
v=
t
y = vt + y0 = 9.8m s × 2s + 0 =19.6m
1 2
y = y0 + v0t + at
2
1
y = 0 + 0 × 2s + 9.8m s 2 (2s)2 =19.6m
2
Or:
35 m
y0 = 0 m
+y
V = 9.8 m/s
5m
v0 = 0 m/s
Find v and y at t = 3 s
v = v0 + at = 0 + 9.8m s ×3s = 29.4m s
v0 + v 0 + 29.4m s
v=
=
=14.7m s
2
2
V = 19.6 m/s
y - y0
v=
t
15 m
20 m
25 m
30 m
35 m
HELP!
45 m
a = 9.8 m/s2
2
10 m
40 m
y0 = 0 m
y = vt + y0 =14.7m s×3s + 0 = 44.1m
1 2
y = y0 + v0t + at
Or:
2
1
y = 0 + 0 × 3s + 9.8m s 2 (3s)2 = 44.1m
2
V = 29.4 m/s = 66 mph!
y0 = 0 m
+y
5m
10 m
15 m
20 m
25 m
V = 9.8 m/s
v0 = 0 m/s
Can you find v and y at t = 4 s ?
No Peeking, solve
v = 39.2 m/s, y = 78.4 m
it yourself first!
Can you find t and y when v = 25 m/s?
V = 19.6 m/s
No Peeking, solve
t = 2.55 s, y = 31.9 m
it yourself first!
Can you find t and v when y = 10 m?
No Peeking, solve
t = 1.43 s, v = 14 m/s
it yourself first!
30 m
Nice Job, take a break.
35 m
40 m
45 m
a = 9.8 m/s2
V = 29.4 m/s
```