Math Problem Statement

Task 5 from the uploaded image: Fireworks are fired from the roof of a 100-foot building and travel at 84 feet per second. The equation h = -16t^2 + 84t + 100 models the height of the fireworks at any given time t seconds. Questions include: A) How long are the fireworks in the air? B) How high did the fireworks get? C) How high were the fireworks 1 second after they left the roof?

Solution

Let’s go through each part of Task 5 one by one. The task gives us the equation:

h=16t2+84t+100h = -16t^2 + 84t + 100

where:

  • hh is the height of the fireworks in feet,
  • tt is the time in seconds since they were fired.

This equation is a quadratic function that models the height of the fireworks over time.

Part A: How long are the fireworks in the air?

To find how long the fireworks are in the air, we need to determine when they hit the ground, i.e., when h=0h = 0.

  1. Set h=0h = 0: 16t2+84t+100=0-16t^2 + 84t + 100 = 0

  2. Solve this quadratic equation using the quadratic formula: t=b±b24ac2at = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} where a=16a = -16, b=84b = 84, and c=100c = 100.

  3. Substitute these values and solve for tt.

Part B: How high did the fireworks get?

To find the maximum height, we need to determine the vertex of this parabola. The time at which the maximum height occurs is given by:

t=b2at = \frac{-b}{2a}

Substitute a=16a = -16 and b=84b = 84 to find the time at which the fireworks reach their maximum height. Then, substitute this value of tt back into the equation for hh to get the maximum height.

Part C: How high were the fireworks 1 second after they left the roof?

Substitute t=1t = 1 into the equation:

h=16(1)2+84(1)+100h = -16(1)^2 + 84(1) + 100

Calculate this to find the height at t=1t = 1 second.

Would you like a detailed step-by-step solution for each part, or have any specific questions about one of them?


Additional Questions to Explore:

  1. What would happen to the maximum height if the initial velocity were higher than 84 feet per second?
  2. How would the equation change if the building height were different from 100 feet?
  3. What does the negative coefficient of t2t^2 in the equation signify in terms of the fireworks' motion?
  4. Can we determine the total distance traveled by the fireworks until they reach the ground?
  5. What is the significance of the discriminant (b24acb^2 - 4ac) in the context of the time the fireworks stay in the air?

Tip:

For quadratic equations describing motion, the vertex represents the peak or maximum height if the parabola opens downward.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Projectile Motion

Formulas

Quadratic function: h = -16t^2 + 84t + 100
Quadratic formula: t = (-b ± √(b² - 4ac)) / 2a
Vertex formula for maximum height: t = -b / (2a)

Theorems

Quadratic formula
Vertex formula for parabolas

Suitable Grade Level

Grades 9-10