Math Problem Statement

A rocket is fired upward from some initial distance above the ground. Its height in feet, h, above the ground, t seconds after it is fired, is given by h = -16t^2 + 240t + 1216. What is the maximum height (in feet)?

Solution

The equation for the height h(t)h(t) of the rocket as a function of time is:

h(t)=16t2+240t+1216h(t) = -16t^2 + 240t + 1216

We need to find the maximum height of the rocket. For a quadratic function h(t)=at2+bt+ch(t) = at^2 + bt + c, the maximum height occurs at the vertex, which can be found using the formula:

tmax=b2at_{\text{max}} = -\frac{b}{2a}

Here, a=16a = -16 and b=240b = 240. Substituting these values:

tmax=2402(16)=24032=7.5seconds.t_{\text{max}} = -\frac{240}{2(-16)} = \frac{240}{32} = 7.5 \, \text{seconds}.

Next, substitute tmax=7.5t_{\text{max}} = 7.5 into the height equation to find the maximum height:

h(7.5)=16(7.5)2+240(7.5)+1216h(7.5) = -16(7.5)^2 + 240(7.5) + 1216

First, calculate (7.5)2(7.5)^2:

(7.5)2=56.25(7.5)^2 = 56.25

Now substitute:

h(7.5)=16(56.25)+240(7.5)+1216h(7.5) = -16(56.25) + 240(7.5) + 1216

h(7.5)=900+1800+1216=2116feet.h(7.5) = -900 + 1800 + 1216 = 2116 \, \text{feet}.

Thus, the maximum height is:

2116feet\boxed{2116 \, \text{feet}}

Would you like a breakdown of any specific steps, or help with related questions?

Related Questions:

  1. How long does it take for the rocket to hit the ground after being launched?
  2. What is the initial velocity of the rocket when it is launched?
  3. How would the maximum height change if the initial velocity were increased?
  4. At what times is the rocket at a height of 1500 feet?
  5. How do changes in the coefficient of t2t^2 affect the trajectory of the rocket?

Tip:

For quadratic equations describing motion, the vertex formula t=b/(2a)t = -b/(2a) is key to finding the time at which the maximum or minimum occurs.

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Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Vertex of a Parabola
Projectile Motion

Formulas

Vertex formula: t_max = -b/(2a)
Quadratic height equation: h(t) = -16t^2 + bt + c

Theorems

Properties of Quadratic Functions

Suitable Grade Level

Grades 10-12