Chapter 3: Problem 181
A projectile is fired from ground level at an angle of \(8^{\circ}\) with the horizontal. The projectile is to have a range of \(50 \mathrm{~m} .\) Find the minimum velocity necessary to achieve this range.
Short Answer
Expert verified
The minimum velocity is approximately \(42.14 \, \text{m/s}\).
Step by step solution
01
Understanding the Concepts
We are asked to find the minimum velocity needed for a projectile to reach a certain range when launched at a specific angle. The range of a projectile can be determined using the formula:\[ R = \frac{v^2 \sin(2\theta)}{g} \]where:- \( R \) is the range, 50 meters in this case.- \( v \) is the initial velocity.- \( \theta \) is the launch angle, which is \(8^{\circ}\).- \( g \) is the acceleration due to gravity, approximately \(9.81 \, \text{m/s}^2\).
02
Set Up the Equation
We need to solve for the initial velocity \( v \) using the given range of 50 meters and the angle of \(8^{\circ}\). Substitute these values into the range formula:\[ 50 = \frac{v^2 \sin(16^{\circ})}{9.81} \]
03
Solve for Initial Velocity
First, calculate \( \sin(16^{\circ}) \). Using a calculator, \( \sin(16^{\circ}) \approx 0.276 \).Substitute this value into the equation:\[ 50 = \frac{v^2 \times 0.276}{9.81} \]Rearrange the equation to solve for \( v^2 \):\[ v^2 = \frac{50 \times 9.81}{0.276} \]Calculate this value.
04
Compute the Result
Perform the multiplication:\[ 50 \times 9.81 = 490.5 \]Now divide by the sine value:\[ \frac{490.5}{0.276} \approx 1777.17 \]Take the square root:\[ v \approx \sqrt{1777.17} \approx 42.14 \]Thus, the minimum initial velocity is approximately \(42.14 \, \text{m/s}\).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Range of a Projectile
The range of a projectile is an important concept in physics. It determines how far a projectile will travel when launched from a specific point. To calculate this distance, we use the formula:\[ R = \frac{v^2 \sin(2\theta)}{g} \]Let's break this formula down:
- **\( R \)** represents the range of the projectile, or how far it travels horizontally. In this case, we are aiming for a range of 50 meters.
- **\( v \)** is the initial velocity. This is what we need to find in the problem.
- **\( \theta \)** is the launch angle relative to the horizontal, which in our exercise is given as 8 degrees.
- **\( g \)** is the acceleration due to gravity, typically approximated as 9.81 m/s² on Earth's surface.
Initial Velocity Calculation
Calculating initial velocity is crucial in projectile motion problems, especially when you need a projectile to hit a specific target. To find the initial velocity using the given values, we substitute into the formula for range:\[ 50 = \frac{v^2 \sin(16^{\circ})}{9.81} \]Here, 50 meters is the range we're aiming to achieve. We perform the calculations in small steps:
- Calculate the sine of 16°, which results from doubling our 8° launch angle. Using a calculator, \( \sin(16^{\circ}) \approx 0.276 \).
- Next, rearrange the formula to solve for \( v^2 \): \[ v^2 = \frac{50 \times 9.81}{0.276} \]
- Solve to find \( v^2 = 1777.17 \).
Launch Angle
The launch angle greatly influences the path and range of a projectile. In projectile motion, the angle at which the projectile is launched will determine the shape and reach of its trajectory. Here, our given angle is 8 degrees.The formula for range includes \( \sin(2\theta) \), meaning that it multiplies the given angle by two—for an 8 degree launch angle, it's calculated using \( 16^{\circ} \).Let's see why each degree matters:
- Small angles typically result in a flatter trajectory, which decreases the maximum height but increases horizontal travel distance, within certain limits.
- A launch angle of 8 degrees is relatively shallow, enhancing horizontal range for a given speed.
- Altering the angle shifts both the vertical and horizontal components of the velocity, demonstrating why optimizing the angle is crucial.