a) In this part of the problem, we will find the two accelerations of the plane. The initial velocity of the plane was vo= 67.4 m/sec. From t = 0 sec to t = 18 sec, the acceleration of the plane was a₁ = a₁. From t = 18 sec to t = 29 sec, the acceleration of the plane was a2 = -a₂. The velocity of the plane at t = 29 sec is 27.3 m/sec. From t = 0 sec to t = 29 sec, the total distance travelled by the plane was 1419.8 m. i. ii. iii. iv. Sketch a velocity vs. time graph for the motion. What is the velocity of the plane at t = 18 sec? Answer: 45.7 m/sec What is the acceleration a₁? Answer: 1.2 m/sec² What is the acceleration a₂? Answer: 1.7 m/sec² b) In this part of the problem, we will find the total distance the plane would have needed to come to rest. The initial velocity of the plane was vo= 67.4 m/sec. From t = 0 sec to t = 18 sec, the acceleration of the plane was a₁ = a₁ = -1.2 m/sec². From t = 18 sec until the plane comes to rest, the acceleration of the plane was a₂-a₂ = -1.7 m/sec². What is the total distance traveled by the airplane, until it comes to rest? Answer: 1635.8 m. Note that this answer is larger than 1419.8 m. c) In this part of the problem, we will find the total distance the plane would have needed to come to rest, if the reverse thrust was activated immediately on touchdown. The initial velocity of the plane was v0 = 67.4 m/sec. From t = 0 sec until the plane comes to rest, the acceleration of the plane was a2 = -a₂ = -1.7 m/sec². What is the total distance traveled by the airplane, until it comes to rest? Answer: 1336.1 m. Note that this answer is smaller than 1419.8 m.

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ISBN:9781305952300
Author:Raymond A. Serway, Chris Vuille
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Chapter1: Units, Trigonometry. And Vectors
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Problem 1:
a) In this part of the problem, we will find the two accelerations of the plane. The initial
velocity of the plane was v0 = 67.4 m/sec. From t = 0 sec to t = 18 sec, the
acceleration of the plane was a₁ = -a₁. From t = 18 sec to t = 29 sec, the
acceleration of the plane was a₂ = -a₂. The velocity of the plane at t = 29 sec is
27.3 m/sec. From t = 0 sec to t = 29 sec, the total distance travelled by the plane was
1419.8 m.
i.
ii.
iii.
iv.
Sketch a velocity vs. time graph for the motion.
What is the velocity of the plane at t = 18 sec? Answer: 45.7 m/sec
What is the acceleration a₁? Answer: 1.2 m/sec²
What is the acceleration a₂? Answer: 1.7 m/sec²
b) In this part of the problem, we will find the total distance the plane would have needed
to come to rest. The initial velocity of the plane was vo= 67.4 m/sec. From t = 0 sec
to t = 18 sec, the acceleration of the plane was a₁ = a₁ = -1.2 m/sec². From
t = 18 sec until the plane comes to rest, the acceleration of the plane was
a₂-a₂ = -1.7 m/sec². What is the total distance traveled by the airplane, until it
comes to rest? Answer: 1635.8 m. Note that this answer is larger than 1419.8 m.
c) In this part of the problem, we will find the total distance the plane would have needed
to come to rest, if the reverse thrust was activated immediately on touchdown. The
initial velocity of the plane was vo = 67.4 m/sec. From t = 0 sec until the plane comes
to rest, the acceleration of the plane was a₂ = -a₂ = -1.7 m/sec². What is the total
distance traveled by the airplane, until it comes to rest? Answer: 1336.1 m. Note that
this answer is smaller than 1419.8 m.
d) In this part of the problem, we will find the latest possible time the reverse thrust could
have been activated so that the airplane would have safely come to rest on the runway,
without going into the safety runway. The initial velocity of the plane was
Vo = 67.4 m/sec. From t = 0 sec to t = t₁, the acceleration of the plane was
a₁ = a₁ = -1.2 m/sec². From t = t₁ until the plane comes to rest, the acceleration
of the plane was a₂ = -a₂ = -1.7 m/sec². The total distance traveled by the airplane
is 1394.8 m. Let's define the time that the acceleration a2 is present as t₂. Thus, the
total time the plane needs to come to rest is t = t₁ + t₂.
i.
What is the velocity of the plane at t = t₁? Answer: 63.75 m/sec
ii.
iii.
What is the time t₁? Answer: 3.04 sec. Notice that this time is less than 18 sec.
What is the time t₂? Answer: 37.5 sec. Notice that t = t₁ + t₂ = 40.04 sec. This
is slightly larger than the time the plane needs to come to rest in part c, where
the reverse thrust is activated immediately on touchdown (t = D = 39.65 sec).
a2
Transcribed Image Text:Problem 1: a) In this part of the problem, we will find the two accelerations of the plane. The initial velocity of the plane was v0 = 67.4 m/sec. From t = 0 sec to t = 18 sec, the acceleration of the plane was a₁ = -a₁. From t = 18 sec to t = 29 sec, the acceleration of the plane was a₂ = -a₂. The velocity of the plane at t = 29 sec is 27.3 m/sec. From t = 0 sec to t = 29 sec, the total distance travelled by the plane was 1419.8 m. i. ii. iii. iv. Sketch a velocity vs. time graph for the motion. What is the velocity of the plane at t = 18 sec? Answer: 45.7 m/sec What is the acceleration a₁? Answer: 1.2 m/sec² What is the acceleration a₂? Answer: 1.7 m/sec² b) In this part of the problem, we will find the total distance the plane would have needed to come to rest. The initial velocity of the plane was vo= 67.4 m/sec. From t = 0 sec to t = 18 sec, the acceleration of the plane was a₁ = a₁ = -1.2 m/sec². From t = 18 sec until the plane comes to rest, the acceleration of the plane was a₂-a₂ = -1.7 m/sec². What is the total distance traveled by the airplane, until it comes to rest? Answer: 1635.8 m. Note that this answer is larger than 1419.8 m. c) In this part of the problem, we will find the total distance the plane would have needed to come to rest, if the reverse thrust was activated immediately on touchdown. The initial velocity of the plane was vo = 67.4 m/sec. From t = 0 sec until the plane comes to rest, the acceleration of the plane was a₂ = -a₂ = -1.7 m/sec². What is the total distance traveled by the airplane, until it comes to rest? Answer: 1336.1 m. Note that this answer is smaller than 1419.8 m. d) In this part of the problem, we will find the latest possible time the reverse thrust could have been activated so that the airplane would have safely come to rest on the runway, without going into the safety runway. The initial velocity of the plane was Vo = 67.4 m/sec. From t = 0 sec to t = t₁, the acceleration of the plane was a₁ = a₁ = -1.2 m/sec². From t = t₁ until the plane comes to rest, the acceleration of the plane was a₂ = -a₂ = -1.7 m/sec². The total distance traveled by the airplane is 1394.8 m. Let's define the time that the acceleration a2 is present as t₂. Thus, the total time the plane needs to come to rest is t = t₁ + t₂. i. What is the velocity of the plane at t = t₁? Answer: 63.75 m/sec ii. iii. What is the time t₁? Answer: 3.04 sec. Notice that this time is less than 18 sec. What is the time t₂? Answer: 37.5 sec. Notice that t = t₁ + t₂ = 40.04 sec. This is slightly larger than the time the plane needs to come to rest in part c, where the reverse thrust is activated immediately on touchdown (t = D = 39.65 sec). a2
x = x₁ + vot + 1²/1at², v = v₁ + at, (v²) = (v₂)² + 2a^x,
(νο)2
2
1
Ax = (0+¹) At, Atrapezoid = (₁+²) h, Atriangle = bh
2
2
Introduction to the Problem
On December 8, 2005 Southwest Airlines flight 1248, a Boeing 737-700 class jet with 103
persons aboard, attempted to land on a snow-covered runway at Chicago's Midway Airport.
Tragically, the attempt resulted in the death of a child on the ground, as the plane slid far
enough beyond the runway to leave airport property and collide with a car (in which the child
was a passenger) on the road beyond. Both the analysis and prevention of accidents such as
this rely on the kinematics of one-dimensional motion. In this problem we will examine how the
National Transportation Safety Board (NTSB) arrived at the conclusion that "the probable cause
of a fatal runway overrun...was the pilots' failure to use available reverse thrust in a timely
manner to safely slow or stop the airplane after landing." (NTSB press release SB-07-48).
The NTSB report does not give the full range of data available to the official accident
investigators, but it does yield enough details to make a basic check of their findings. According
to the information released to the public, the plane touched down with 4576 feet of regular
runway remaining and an 82 foot runway safety overrun area beyond. The plane was moving at
a ground speed of 131 knots when it touched down. Brakes were employed essentially
immediately, but the pilots failed to completely reverse the engine thrust until 18 seconds after
touchdown (for comparison, four of the five air carrier airplanes landing in the 25 minutes prior
to the accident reversed engine thrust within 4 seconds of touchdown, and all did so within 6
seconds). At approximately 29 seconds after touchdown the plane left the back of the runway
safety area moving at a ground speed of about 53 knots.
Transcribed Image Text:x = x₁ + vot + 1²/1at², v = v₁ + at, (v²) = (v₂)² + 2a^x, (νο)2 2 1 Ax = (0+¹) At, Atrapezoid = (₁+²) h, Atriangle = bh 2 2 Introduction to the Problem On December 8, 2005 Southwest Airlines flight 1248, a Boeing 737-700 class jet with 103 persons aboard, attempted to land on a snow-covered runway at Chicago's Midway Airport. Tragically, the attempt resulted in the death of a child on the ground, as the plane slid far enough beyond the runway to leave airport property and collide with a car (in which the child was a passenger) on the road beyond. Both the analysis and prevention of accidents such as this rely on the kinematics of one-dimensional motion. In this problem we will examine how the National Transportation Safety Board (NTSB) arrived at the conclusion that "the probable cause of a fatal runway overrun...was the pilots' failure to use available reverse thrust in a timely manner to safely slow or stop the airplane after landing." (NTSB press release SB-07-48). The NTSB report does not give the full range of data available to the official accident investigators, but it does yield enough details to make a basic check of their findings. According to the information released to the public, the plane touched down with 4576 feet of regular runway remaining and an 82 foot runway safety overrun area beyond. The plane was moving at a ground speed of 131 knots when it touched down. Brakes were employed essentially immediately, but the pilots failed to completely reverse the engine thrust until 18 seconds after touchdown (for comparison, four of the five air carrier airplanes landing in the 25 minutes prior to the accident reversed engine thrust within 4 seconds of touchdown, and all did so within 6 seconds). At approximately 29 seconds after touchdown the plane left the back of the runway safety area moving at a ground speed of about 53 knots.
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