Math Problem Statement

A ball is thrown vertically upward with an initial velocity of 12 m/s. Its height, h(t) metres after t seconds, is given by the equation h(t) = -2t^2 + 12t + 2.3. The maximum height, to the nearest tenth, reached by the ball is ______ m.

Solution

To solve for the maximum height reached by the ball, we need to analyze the given equation for height, which is:

h(t)=2t2+12t+2.3h(t) = -2t^2 + 12t + 2.3

This is a quadratic equation of the form:

h(t)=at2+bt+ch(t) = at^2 + bt + c

where a=2a = -2, b=12b = 12, and c=2.3c = 2.3.

Step 1: Find the time tt at which the ball reaches its maximum height

In a quadratic equation, the maximum (or minimum) value occurs at t=b2at = \frac{-b}{2a}. Using this formula:

t=122(2)=124=3secondst = \frac{-12}{2(-2)} = \frac{-12}{-4} = 3 \, \text{seconds}

Step 2: Substitute t=3t = 3 into the height equation to find the maximum height

Now, we substitute t=3t = 3 into the equation h(t)h(t):

h(3)=2(3)2+12(3)+2.3h(3) = -2(3)^2 + 12(3) + 2.3 h(3)=2(9)+36+2.3h(3) = -2(9) + 36 + 2.3 h(3)=18+36+2.3h(3) = -18 + 36 + 2.3 h(3)=18+2.3=20.3metersh(3) = 18 + 2.3 = 20.3 \, \text{meters}

Conclusion:

The maximum height reached by the ball is 20.3 meters, to the nearest tenth.

Would you like further clarification on any of the steps?

Here are 5 related questions:

  1. How do we know that this quadratic equation has a maximum and not a minimum?
  2. What happens to the ball's height after it reaches its maximum?
  3. How can we find when the ball hits the ground using this equation?
  4. How would the height equation change if the initial velocity were different?
  5. How do air resistance and gravity influence the motion described by this equation?

Tip: In quadratic functions, if the coefficient of t2t^2 is negative, the function has a maximum value; if it's positive, it has a minimum.

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Math Problem Analysis

Mathematical Concepts

Quadratic Equations
Vertex of a Parabola
Kinematics

Formulas

h(t) = -2t^2 + 12t + 2.3
t = -b / 2a for the vertex of a parabola

Theorems

Vertex formula for parabolas

Suitable Grade Level

Grades 9-12