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A rocket test projectile is launched skyward at 88 m/sec (198 mi/hr). How high does it go?. 8 8 m/sec. v o = ? v final = ? a = ? time to reach peak, t = ? height reached, x = ?. - 9.8 m/sec 2. When does it peak? What has happened by that point?. - PowerPoint PPT Presentation
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A rocket test projectile is launched skyward at 88 m/sec (198 mi/hr). How high does it go?
vo = ?vfinal = ?
a = ?
time to reach peak, t = ?height reached, x = ?
When does it peak? What has happened by that point?
v = 0 tsec
m
sec
m )8.9(88 2−+=
tsec
m
sec
m )8.9(88 2−=−
tsec
msecm
=−−
28.988
= 9 sec
So 2
2
1
00attvxx +=− )81)(8.9()9)(88( 2
21
2 secsecsec
m
sec
m −+
= 792m – 396.9m= 395 m (1/4 mile)
9.8 m/sec2
88 m/sec
A ball is thrown straight upward and caught when it returns to the height from which it was released.
1. At its peak position, the ball’sA. instantaneous velocity is maximum.B. instantaneous velocity is zero.C. instantaneous acceleration is zero.D. both B & C are true.
2. The time to fall back from its peak position is A. greater than B. equal to C. less than
the time it took to climb that high.
3. The speed it builds up to downward by the moment it is caught is A. greater than B. equal to C. less than
the speed it was thrown upward with.
For objects for which air friction is negligible,
time up = time downspeed down = speed up
Two spheres of identical mass areReleased when the mechanism aboveIs triggered. One sphere is launched Horizontally by a spring, the other is simultaneously dropped from rest.
A. The launched sphere will reach the ground first.B. Both spheres touch ground at the same time. C. The dropped sphere reaches the ground first.
Galileo’s critics argued that if the earth moved:
A stone is flung horizontally at 8 m/secfrom a point 1100 meters above the baseof a cliff.How far away from the cliff does it land?
?
?
/80.9
11002
=Δ=
−==
−=Δ
xt
smga
my or +1100m
+9.80m/s
Careful!!!Actually ay = 9.8m/s2
ax = ?0
0
/8
0
0
=
=
y
x
v
smv
VERTICALLY2
221 )80.9(01100 t
s
mm −+=− t = 15 sec
HORIZONTALLY
)15)(/8( ssmx =Δ Δx = 120 m
Its y-component of motionis like dropping from rest!
5
15
25
35
45
10
20
30
40
50
5 10 15 20 25 30 35
Weight Support (floor)
Adding all these supporting forces together
some pull left,some pull right,some pull forward,some pull back
all tend to pull UP!
(a tug-of-war balancing)
Styrofoam bridge
weighted at center
Pressure applied to rigid glass bar