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Ch. 7 - Logarithmic, Exponential Functions, and Hyperbolic Functions
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Briggs 3rd EditionCh. 7 - Logarithmic, Exponential Functions, and Hyperbolic Functions문제 7.3.97d
7장, 문제 7.3.97d

Terminal velocity Refer to Exercises 95 and 96.


d. How tall must a cliff be so that the BASE jumper (m = 75 kg and k = 0.2) reaches 95% of terminal velocity? Assume the jumper needs at least 300 m at the end of free fall to deploy the chute and land safely.

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1
Recall the velocity function for an object falling with air resistance proportional to velocity: \(v(t) = v_{\text{terminal}} (1 - e^{-\frac{k}{m} t})\), where \(v_{\text{terminal}} = \frac{mg}{k}\).
Calculate the terminal velocity \(v_{\text{terminal}}\) using the given mass \(m = 75\) kg, gravitational acceleration \(g = 9.8\) m/s², and drag coefficient \(k = 0.2\): \(v_{\text{terminal}} = \frac{75 \times 9.8}{0.2}\).
Set the velocity to 95% of terminal velocity: \(v(t) = 0.95 \times v_{\text{terminal}}\), and solve for time \(t\) using the velocity formula: \(0.95 = 1 - e^{-\frac{k}{m} t}\).
Rearrange to isolate the exponential term: \(e^{-\frac{k}{m} t} = 1 - 0.95 = 0.05\), then take the natural logarithm to solve for \(t\): \(t = -\frac{m}{k} \ln(0.05)\).
Find the distance fallen during time \(t\) by integrating the velocity function or using the position formula: \(s(t) = v_{\text{terminal}} \left(t + \frac{m}{k} e^{-\frac{k}{m} t}\right)\). Add the 300 m needed for chute deployment to find the total cliff height.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Terminal Velocity

Terminal velocity is the constant speed an object reaches when the force of gravity is balanced by the drag force from air resistance. At this point, acceleration stops, and the object falls at a steady speed. It depends on factors like mass, drag coefficient, and air density.
추천 영상:
가이드 코스
06:29
Derivatives Applied To Velocity

Differential Equations in Motion with Air Resistance

The motion of a falling object with air resistance is modeled by a differential equation balancing gravitational force and drag force. Solving this equation gives velocity as a function of time or distance, which is essential to determine how long or how far it takes to reach a certain fraction of terminal velocity.
추천 영상:
07:39
Classifying Differential Equations

Free Fall Distance and Safety Constraints

In problems involving BASE jumping, the total height must account for the distance needed to reach a target velocity and the safety margin for parachute deployment. Understanding how to partition the total height into acceleration and deceleration zones ensures the jumper can safely land.
추천 영상:
가이드 코스
07:39
Pumping Liquids
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