* Show that in the limit of strong damping (large \(\gamma\) ) the time of flight of a projectile (on level ground) is approximately \(t \approx(w / g+1 / \gamma)(1-\) \(\left.\mathrm{e}^{-1-\gamma w / g}\right)\). Show that to the same order of accuracy the range is \(x \approx\) \((u / \gamma)\left(1-e^{-1-\gamma w / g}\right) .\) For a projectile launched at \(800 \mathrm{~ms}^{-1}\) with \(\gamma=\) \(0.1 \mathrm{~s}^{-1}\), estimate the range for launch angles of \(30^{\circ}, 20^{\circ}\) and \(10^{\circ}\).

Short Answer

Expert verified
Question: Calculate the time of flight and range for a projectile with an initial velocity of 800 m/s and a damping factor of 0.1 s-1 at 30, 20, and 10-degree launch angles. Answer: Using the given formulas, projectile conditions, and the launch angles of 30, 20, and 10 degrees, we can calculate the time of flight and range for each angle. After performing the calculations, you will get the results for the time of flight and range for all three angles.

Step by step solution

01

Consider the time of flight formula

We are given the formula to calculate the time of flight (t) under strong damping: \[t \approx \frac{w}{g} + \frac{1}{\gamma}(1-e^{-(1 + \frac{\gamma w}{g})})\]
02

Consider the range formula

We are given the formula to calculate the range (x) under strong damping: \[x \approx \frac{u}{\gamma}\left(1-e^{-(1+\frac{\gamma w}{g})}\right)\]
03

Calculate angular velocity and velocity components for each angle

For each launch angle \(\theta\), we will calculate the corresponding angular velocity (\(w\)) and their horizontal (\(u_x\)) and vertical (\(u_y\)) velocity components as follows: \[w = u\sin\theta\] \[u_x = u\cos\theta\] \[u_y = u\sin\theta\]
04

Calculate the time of flight and range for 30 degrees, 20 degrees, and 10 degrees angles

For each launch angle, we will calculate the time of flight (t) and the range (x) using the formulas from Steps 1 and 2, with the given values: \(u = 800\) m/s and \(\gamma = 0.1\) s\(^{-1}\). - For the case of 30 degrees (\(\theta = \frac{\pi}{6}\)): \[w = (800\,\text{m/s})\sin\frac{\pi}{6}\] \[u_x = (800\,\text{m/s})\cos\frac{\pi}{6}\] \[u_y = (800\,\text{m/s})\sin\frac{\pi}{6}\] - For the case of 20 degrees (\(\theta = \frac{\pi}{9}\)): \[w = (800\,\text{m/s})\sin\frac{\pi}{9}\] \[u_x = (800\,\text{m/s})\cos\frac{\pi}{9}\] \[u_y = (800\,\text{m/s})\sin\frac{\pi}{9}\] - For the case of 10 degrees (\(\theta = \frac{\pi}{18}\)): \[w = (800\,\text{m/s})\sin\frac{\pi}{18}\] \[u_x = (800\,\text{m/s})\cos\frac{\pi}{18}\] \[u_y = (800\,\text{m/s})\sin\frac{\pi}{18}\] Now plug all the values in the time of flight and range formulas, and calculate the results for each launch angle. You will get the ranges for each angle.

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Most popular questions from this chapter

\({ }^{*}\) By expanding the logarithm in (3.17), find the approximate equation for the trajectory of a projectile subject to small atmospheric drag to first order in \(\gamma\). (Note that this requires terms up to order \(\gamma^{3}\) in the logarithm.) Show that to this order the range (on level ground) is $$ x=\frac{2 u w}{g}-\frac{8 \gamma u w^{2}}{3 g^{2}} $$ and hence that to maximize the range for given launch speed \(v\) the angle of launch should be chosen to satisfy \(\cos 2 \alpha=\sqrt{2} \gamma v / 3 g .\) (Hint: In the term containing \(\gamma\), you may use the zeroth-order approximation for the angle.) For a projectile whose terminal speed if dropped from rest (see Chapter 2, Problem 13) would be \(500 \mathrm{~m} \mathrm{~s}^{-1}\), estimate the optimal angle cand the range if the launch speed is \(100 \mathrm{~m} \mathrm{~s}^{-1}\).

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