Math Problem Statement

A ball is launched at an angle of 45.0° above the horizontal. It reaches a maximum height of 40.0 m. What is the range of the projectile?

Solution

Let's break down the problem presented in the image:

  • Given Information:
    • A ball is launched at an angle of 45° above the horizontal.
    • It reaches a maximum height of 40.0 m.

You are asked to find the range of the projectile, which is the horizontal distance the ball travels before hitting the ground.

Step-by-Step Solution:

1. Find the initial velocity using maximum height:

The formula for maximum height HH in projectile motion is:

H=v02sin2θ2gH = \frac{v_0^2 \sin^2 \theta}{2g}

Where:

  • HH = maximum height (40.0 m)
  • v0v_0 = initial velocity (unknown)
  • θ\theta = angle of launch (45°)
  • gg = acceleration due to gravity (9.8 m/s²)

Rearranging to solve for v0v_0:

v02=2gHsin2θv_0^2 = \frac{2gH}{\sin^2 \theta}

Substitute the known values:

v02=2×9.8×40.0sin245v_0^2 = \frac{2 \times 9.8 \times 40.0}{\sin^2 45^\circ}

Since sin45=12\sin 45^\circ = \frac{1}{\sqrt{2}}, we can now calculate the value of v0v_0.

2. Calculate the Range:

The range RR of a projectile is given by the formula:

R=v02sin2θgR = \frac{v_0^2 \sin 2\theta}{g}

Since sin90=1\sin 90^\circ = 1 (because 2×45=902 \times 45^\circ = 90^\circ), this simplifies to:

R=v02gR = \frac{v_0^2}{g}

Now, I'll calculate the exact values for both v0v_0 and RR.The initial velocity v0v_0 is approximately 39.60 m/s, and the range RR of the projectile is approximately 160.0 meters.

Thus, the correct answer for the range is 160.0 m, not 40.0 m as selected.

Do you need any further clarifications or details? Here are some related questions to consider:

  1. How would the range change if the angle of projection were increased or decreased?
  2. What is the total time of flight for this projectile?
  3. How would air resistance affect the range of the projectile?
  4. Can you derive the range formula from the basic kinematic equations?
  5. How does the initial velocity influence both the maximum height and the range?

Tip: The range is maximized at a launch angle of 45°, but it varies if the launch angle or initial velocity changes.

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Math Problem Analysis

Mathematical Concepts

Projectile Motion
Kinematics
Trigonometry

Formulas

H = (v0^2 * sin^2(θ)) / (2g)
R = (v0^2 * sin(2θ)) / g

Theorems

Range of a Projectile
Kinematic Equations of Motion

Suitable Grade Level

Grades 10-12