What is the stuntman's velocity, displacement, and
acceleration while falling. Given: times at 1,2,3 sec
Proj. Motion guidelines
„
„
horiz. & vert. motion are considered
„
SEPARATELY
„
„
„
horiz motion: not affected by
y acceleration
vert motion: affected by acceleration due to
gravity ((--9.8 m/s2)
Air resistance is ignored
„ tup = tdown (only when take-off and landing height are the same)
„ Vv at apex = 0
„
Horizontal
motion
„
„
dh= vh (t)
Vertical motion
„ vf = vi + at
„ vf2 = vi2 + 2ad
„ d = vit + (1/2)at2
vf = vi + at
(-9.8 m/s2) (1s)
vf = o + (vf = -9.8 m/s
Time
0s
velocity
0
displacement
0
2s
-9.8 m/s -4.9 m
-19.6 m/s -19.6 m
3s
-29.4 m/s -44.1 m
1s
dh= vh (t)
Vertical motion
„ vf = vi + at
„ vf2 = vi2 + 2ad
„ d = vit + (1/2)at2
vf = vi + at
(-9.8 m/s2) (1s)
vf = o + (vf = -9.8 m/s
What is the stuntman's velocity displacement and
acceleration while falling at seconds 00-3?
„
Horizontal
motion
Time
0s
1s
velocity
0
displacement
0
-9.8 m/s
-4.9 m
acceleration
0
-9.8 m/s2
2s
-9.8 m/s2
3s
d = vit + (1/2)at2
(-9.8 m/s2) (1s)2
d = o + (1/2) (d = -4.9 m
Bungee jumping Skippers Canyon, NZ
acceleration
0
-9.8 m/s2
-9.8 m/s2
d = vit + (1/2)at2
(-9.8 m/s2) (1s)2
d = o + (1/2) (d = -4.9 m
Bungee jumping Skippers Canyon, NZ
What was the vertical velocity at the instant the
„Given:
bungee began to lengthen?
„
Horizontal
motion
„
Vertical motion
„ vf = vi + at
„ vf2 = vi2 + 2ad
„ d = vit + (1/2)at2
„
dh= vh (t)
-102 meter drop
Vi = -3.0 m/s
vf2 = vi2 + 2ad
vf2 = -3.02 + 2(
2(--9.8)(
9.8)(--102)
vf2 = 9 + 1999
vf = -44.81m/s
Trampolinist goes up.. What is the time to
.
peak and how high did they jump? „Given:
„
„
„
Vi = 10.5 m/s
Horizontal
motion
Step 1: resolve net velocity
cos 23.2°
23.2° * 9.8m/s
9.8 m/s
23.2°°
23.2
vh = 9.01 m/s
dh= vh (t)
Sin 23.2
23.2°° * 9.8m/s
Vertical motion
„ vf = vi + at
„ vf2 = vi2 + 2ad
„ d = vit + (1/2)at2
vf = vi + at
vv = 3.86 m/s
St 2:
Step
2 tup
vf = vi + at
d = vit + (1/2)at2
0 = 5.0 m/s + ((--9.8 m/s2) (t)
-5.0 m/s
-9.8 m/s2 = 0.51 s
d = (5.0 m/s) (.51 s) + (1/2)
(-9.8 m/s2) (.51s)2
d = 1.28 m
Long jumper: How high and how far did they go?
Step 4: total time
9.8 m/s
tup = tdn
23.2°°
23.2
.394 s + .394 s = .788 s
Step 5: dh
dh= vh (t)
(9.01 m/s) (.788 s) =
Long jumper: How high and how far did they go?
Dh = 7.10 m
„Given:
tup = tdn
Step 3: dv
dv = vit + (1/2)at2
dv= (3.86 m/s) (.394 s) +
(1/2) ((-9.8 m/s2) (.394 s)2
vf = 3.86 m/s + ((--9.8 m/s2) (tup)
-3.86 m/s
-9.8 m/s2
„Given:
tup = tdn
= .394 s
dv= .76 m