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A projectile is launched from ground level at an angle of \(12.0^{\circ}\) above the horizontal. It returns to ground level. To what value should the launch angle be adjusted, without changing the launch speed, so that the range doubles?

Short Answer

Expert verified
Adjust the angle to approximately \( 37.2^{\circ} \) to double the range.

Step by step solution

01

Understanding the Range Formula

The range \( R \) of a projectile launched with an initial speed \( v_0 \) at an angle \( \theta \) is given by the formula \( R = \frac{v_0^2 \sin(2\theta)}{g} \), where \( g \) is the acceleration due to gravity. At the initial angle of \( 12.0^{\circ} \), this formula applies to find the initial range.
02

Calculating the Initial Range

Using the formula from Step 1, the initial range \( R_i \) can be obtained by inserting the initial angle \( \theta_i = 12.0^{\circ} \). The initial range \( R_i \) is \( \frac{v_0^2 \sin(24^{\circ})}{g} \).
03

Setting Up the New Range Equation

We want the new range \( R_f \) to be double the initial range: \( R_f = 2R_i \). Substituting the expression for \( R_i \), we have \( R_f = \frac{2v_0^2 \sin(24^{\circ})}{g} \).
04

Solving for the New Angle

To achieve the new range, use the formula for range with the desired angle \( \theta_f \): \( R_f = \frac{v_0^2 \sin(2\theta_f)}{g} \). Equate this expression to the one obtained in Step 3: \( \frac{v_0^2 \sin(2\theta_f)}{g} = \frac{2v_0^2 \sin(24^{\circ})}{g} \). Simplify to get \( \sin(2\theta_f) = 2\sin(24^{\circ}) \).
05

Calculating \( \theta_f \)

Since \( \sin(2\theta_f) = 2\sin(24^{\circ}) \), find the value of \( \theta_f \) by rearranging and using inverse trigonometry or calculators. This gives \( 2\theta_f = \sin^{-1}(2\sin(24^{\circ})) \), then divide by 2 to find \( \theta_f \). Be aware that \( 2\theta_f \) must be less than or equal to \( 90^{\circ} \) as the maximum angle for a projectile is \( 45^{\circ} \). Calculate to find \( \theta_f \).
06

Conclusion

After performing the calculations based on trigonometric functions with the constraint of projectile angles, \( \theta_f \) is resolved. Ensure the calculations respect both trigonometric identities and the fall-back angle limitations.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Range Formula
The Range Formula is a key part of understanding projectile motion. It's a mathematical way to predict how far an object will travel when launched at a given speed and angle. The formula is:\[ R = \frac{v_0^2 \sin(2\theta)}{g} \]where:
  • \( R \) represents the range, or the horizontal distance traveled by the projectile.
  • \( v_0 \) is the initial velocity at which the projectile is launched.
  • \( \theta \) is the launch angle above the horizontal direction.
  • \( g \) is the acceleration due to gravity, approximately \( 9.8 \ \text{m/s}^2 \).
This equation shows that the range depends on the square of the initial speed and the sine of twice the launch angle. This is why understanding trigonometry is crucial for calculating projectile motion correctly. The range increases if you increase the initial speed or adjust the angle to optimize the value of \( \sin(2\theta) \).
Trigonometry
Trigonometry plays a significant role in solving projectile motion problems, especially those involving angles. Here's why:
  • Trigonometry concepts like sine, cosine, and tangent help in decomposing forces and calculating distances in physics.
  • In the range formula, the term \( \sin(2\theta) \) is pivotal. It tells us how effectively we use the launch speed to achieve maximum range.
In projectile problems, when doubling the launch angle, as derived from \( \sin(2\theta) \), mathematical concepts like angle identity and inverse trigonometry are necessary. As seen in our problem, calculating the new angle required using \( \sin^{-1} \). This shows the close link between trigonometry and the movement patterns of objects under gravity. By understanding how to manipulate these trigonometric functions, you can accurately predict changes and outcomes in the flight paths of projectiles.
Angle Optimization
Angle Optimization refers to finding the ideal angle for a projectile's launch to maximize or achieve a specific outcome, like stretching the range as required in our problem. Based on the range formula, the best angle to maximize the horizontal range is 45 degrees.However, in the given problem, the launch angle had to be adjusted to double the range. Initially, the projectile was launched at \(12.0^{\circ}\) but needed an adjustment. The adjusted launch angle \( \theta_f \) was calculated by setting up equations with trigonometric identities and solving for \( \theta_f \). This ensures that the new range is exactly twice the original.Though 45 degrees is optimal for maximization, specific problems demand unique angles based on conditions provided. By effectively manipulating angle values through sin and cos insights, you can solve varied physics challenges.
Physics Problem Solving
Physics Problem Solving involves applying theoretical concepts to real-world scenarios. In projectile motion, this means using physics principles and formulas to predict or manipulate outcomes. First, understand what is being asked. Here, the goal was to double the range without changing the initial launch speed.
Next, break down the steps using physics equations. Start from basic principles, like the range formula.
Once all values are plugged in, solve algebraically while respecting any limitations or nuances, such as maximum angle constraints. Solving such problems requires:
  • A grasp of involved physics laws and equations.
  • Logical problem breakdown into manageable parts.
  • Steady application of mathematical skills.
Whether you're calculating a perfect launch angle or doubling a projectile's reach, physics problem solving is about bringing theory into practice, guided by step-by-step analysis and calculation.

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