Practice Problem: For a fifth set of maneuvers, the astronaut's partner calculates her average acceleration over the 2 s interval to be -0.5 m/s². If the initial velocity of the astronaut was -0.4 m/s, what was her final velocity? Did she speed up or slow down over the 2 s interval? Answers: -1.4 m/s, speed up. ino

College Physics
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ISBN:9781305952300
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Publisher:Raymond A. Serway, Chris Vuille
Chapter1: Units, Trigonometry. And Vectors
Section: Chapter Questions
Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...
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I just need the practice problem solved with work shown. The rest of the image provides the information needed to solve the problem. The correct answer is also provided to check work.  The info starts at example 2.3

Units: m/s²
Notes:
dav, x
V2x
Ulx
12 - 11
AUx
At
|
S
(2.3)
Average acceleration is a vector.
• It describes how the velocity is changing with time.
●
• The sign of the average acceleration is not necessarily the same as the sign of the
velocity. Furthermore, if the object is slowing down, then it does not necessarily
follow that the acceleration is negative. Similarly, if the object is speeding up, it does
not necessarily follow that it has positive acceleration.
U2x = 1.2 m/s (speeding up);
(a) U₁x = 0.8 m/s,
(b) Ulx = 1.6 m/s,
(c) U₁x = -0.4 m/s,
U2x =
1.2 m/s (slowing down);
U2x =
-1.0 m/s (speeding up);
(d) v₁x = -1.6m/s,
Ulx
V2x = -0.8 m/s (slowing down).
If t₁ = 2 s and t₂ = 4s in each case, find the average acceleration for each set of data.
close to 200 m
the average v
is because, fr
displacement
EXAMPLE 2.3 Acceleration in a space walk
In this example we will use Equation 2.3 to calculate the acceleration of an astronaut on a space walk. The
astronaut has left the space shuttle on a tether to test a new personal maneuvering device. She moves along
a straight line directly away from the shuttle. Her onboard partner measures her velocity before and after
certain maneuvers, and obtains these results:
Transcribed Image Text:Units: m/s² Notes: dav, x V2x Ulx 12 - 11 AUx At | S (2.3) Average acceleration is a vector. • It describes how the velocity is changing with time. ● • The sign of the average acceleration is not necessarily the same as the sign of the velocity. Furthermore, if the object is slowing down, then it does not necessarily follow that the acceleration is negative. Similarly, if the object is speeding up, it does not necessarily follow that it has positive acceleration. U2x = 1.2 m/s (speeding up); (a) U₁x = 0.8 m/s, (b) Ulx = 1.6 m/s, (c) U₁x = -0.4 m/s, U2x = 1.2 m/s (slowing down); U2x = -1.0 m/s (speeding up); (d) v₁x = -1.6m/s, Ulx V2x = -0.8 m/s (slowing down). If t₁ = 2 s and t₂ = 4s in each case, find the average acceleration for each set of data. close to 200 m the average v is because, fr displacement EXAMPLE 2.3 Acceleration in a space walk In this example we will use Equation 2.3 to calculate the acceleration of an astronaut on a space walk. The astronaut has left the space shuttle on a tether to test a new personal maneuvering device. She moves along a straight line directly away from the shuttle. Her onboard partner measures her velocity before and after certain maneuvers, and obtains these results:
36
CHAPTER 2 Motion Along a Straight Line
SOLUTION
SET UP We use the diagram in Figure 2.11 to organize our data.
Part (a)
Part (b)
Part (c)
Part (d)
BEFORE
Vlx = 0.8 m/s
Vlx = 1.6 m/s
U1x
Vlx = -0.4 m/s
Ulx = -1.6 m/s
AFTER
U2x
→→→→x
1.2 m/s
dansla
U2x = 1.2 m/s
U2x = -0.8 m/s
at boong sa
A FIGURE 2.11 We can use a sketch and table to organize the
information given in the problem.
SOLVE To find the astronaut's average acceleration in each case, we use
Aux/At.
the definition of average acceleration (Equation 2.3): Aav,x
The time interval is At = 2.0 s in all cases; the change in velocity in
each case is AUx = U2x - Ulx.
Δυχ
1.2 m/s 0.8 m/s
Imor
Part (a): dav, x
Part (b): dav, x
Part (c): dav, x
Part (d): dav, x
=
=
=
-
4s2s
1.2 m/s - 1.6 m/s
= -0.2 m/s²;
4s2s agabova sil
= +0.2 m/s²;
-1.0 m/s - (-0.4 m/s)
4s-2s
-
-0.8 m/s (-1.6 m/s)
4s2s
=
-0.3 m/s²;
=
-
REFLECT The astronaut speeds up in cases (a) and (c) and slows down
in (b) and (d), but the average acceleration is positive in (a) and (d) and
U2x = -1.0 m/s oor negative in (b) and (c). So negative acceleration does not necessarily
indicate a slowing down.
-
362
2014
20
+0.4 m/s². VAS
to bolovadi nodw
Practice Problem: For a fifth set of maneuvers, the astronaut's partner
calculates her average acceleration over the 2 s interval to be -0.5 m/s².
If the initial velocity of the astronaut was -0.4 m/s, what was her final
velocity? Did she speed up or slow down over the 2 s interval? Answers:
-1.4 m/s, speed up.
pony
10000
Example 2.3 raises the question of what the sign of acceleration means and how
relates to the signs of displacement and velocity, Recou
istalle
x component) is defined
Transcribed Image Text:36 CHAPTER 2 Motion Along a Straight Line SOLUTION SET UP We use the diagram in Figure 2.11 to organize our data. Part (a) Part (b) Part (c) Part (d) BEFORE Vlx = 0.8 m/s Vlx = 1.6 m/s U1x Vlx = -0.4 m/s Ulx = -1.6 m/s AFTER U2x →→→→x 1.2 m/s dansla U2x = 1.2 m/s U2x = -0.8 m/s at boong sa A FIGURE 2.11 We can use a sketch and table to organize the information given in the problem. SOLVE To find the astronaut's average acceleration in each case, we use Aux/At. the definition of average acceleration (Equation 2.3): Aav,x The time interval is At = 2.0 s in all cases; the change in velocity in each case is AUx = U2x - Ulx. Δυχ 1.2 m/s 0.8 m/s Imor Part (a): dav, x Part (b): dav, x Part (c): dav, x Part (d): dav, x = = = - 4s2s 1.2 m/s - 1.6 m/s = -0.2 m/s²; 4s2s agabova sil = +0.2 m/s²; -1.0 m/s - (-0.4 m/s) 4s-2s - -0.8 m/s (-1.6 m/s) 4s2s = -0.3 m/s²; = - REFLECT The astronaut speeds up in cases (a) and (c) and slows down in (b) and (d), but the average acceleration is positive in (a) and (d) and U2x = -1.0 m/s oor negative in (b) and (c). So negative acceleration does not necessarily indicate a slowing down. - 362 2014 20 +0.4 m/s². VAS to bolovadi nodw Practice Problem: For a fifth set of maneuvers, the astronaut's partner calculates her average acceleration over the 2 s interval to be -0.5 m/s². If the initial velocity of the astronaut was -0.4 m/s, what was her final velocity? Did she speed up or slow down over the 2 s interval? Answers: -1.4 m/s, speed up. pony 10000 Example 2.3 raises the question of what the sign of acceleration means and how relates to the signs of displacement and velocity, Recou istalle x component) is defined
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