Math Problem Statement

The following function gives the height, h metres, of a batted baseball as a function of the time, t seconds, since the ball was hit. 

h=-6(t-2.5) squared +38.5

a)  What was the maximum height of the ball?

b)  What was the height of the ball when it was hit?

c)  How many seconds after it was hit did the ball hit the ground, to the nearest second?  

d)  Find the height of the ball 1 second after it was hit.

e)  Over what time interval is the height of the baseball greater than 25 m?  Answer accurate to one decimal place.

Solution

Let’s analyze and solve the given quadratic function step by step.

The height of the baseball is modeled by:
h(t)=6(t2.5)2+38.5h(t) = -6(t - 2.5)^2 + 38.5

a) Maximum Height of the Ball

The function is written in vertex form:
h(t)=a(th)2+kh(t) = a(t - h)^2 + k
Here, the vertex of the parabola (h,k)(h, k) represents the maximum point since the coefficient a=6a = -6 is negative (downward opening parabola).

  • From the equation, h=2.5h = 2.5 and k=38.5k = 38.5.
  • The maximum height is k=38.5k = 38.5 m.

Answer (a): The maximum height of the ball is 38.5 m.


b) Height of the Ball When It Was Hit

To find the height of the ball when it was hit (t=0t = 0), substitute t=0t = 0 into the equation: h(0)=6(02.5)2+38.5h(0) = -6(0 - 2.5)^2 + 38.5 h(0)=6(2.5)2+38.5=6(6.25)+38.5=37.5+38.5=1h(0) = -6(2.5)^2 + 38.5 = -6(6.25) + 38.5 = -37.5 + 38.5 = 1

Answer (b): The height of the ball when it was hit is 1 m.


c) Time for the Ball to Hit the Ground

The ball hits the ground when h(t)=0h(t) = 0. Solve for tt: 6(t2.5)2+38.5=0-6(t - 2.5)^2 + 38.5 = 0 6(t2.5)2=38.5(t2.5)2=38.56(t2.5)2=6.4167-6(t - 2.5)^2 = -38.5 \quad \Rightarrow \quad (t - 2.5)^2 = \frac{38.5}{6} \quad \Rightarrow \quad (t - 2.5)^2 = 6.4167 Take the square root: t2.5=±6.4167t2.5=±2.534t - 2.5 = \pm \sqrt{6.4167} \quad \Rightarrow \quad t - 2.5 = \pm 2.534 t=2.5+2.534ort=2.52.534t = 2.5 + 2.534 \quad \text{or} \quad t = 2.5 - 2.534 t=5.034ort=0.034t = 5.034 \quad \text{or} \quad t = -0.034 Since time cannot be negative, the ball hits the ground at t=5.034t = 5.034 seconds.

To the nearest second, 5 seconds.

Answer (c): The ball hits the ground 5 seconds after being hit.


d) Height of the Ball 1 Second After Being Hit

Substitute t=1t = 1 into the equation: h(1)=6(12.5)2+38.5h(1) = -6(1 - 2.5)^2 + 38.5 h(1)=6(1.5)2+38.5=6(2.25)+38.5=13.5+38.5=25h(1) = -6(-1.5)^2 + 38.5 = -6(2.25) + 38.5 = -13.5 + 38.5 = 25

Answer (d): The height of the ball 1 second after it was hit is 25 m.


e) Time Interval When the Ball’s Height is Greater Than 25 m

Solve for tt when h(t)>25h(t) > 25: 6(t2.5)2+38.5>25-6(t - 2.5)^2 + 38.5 > 25 6(t2.5)2>13.5(t2.5)2<13.56(t2.5)2<2.25-6(t - 2.5)^2 > -13.5 \quad \Rightarrow \quad (t - 2.5)^2 < \frac{13.5}{6} \quad \Rightarrow \quad (t - 2.5)^2 < 2.25 Take the square root: t2.5<2.25andt2.5>2.25t - 2.5 < \sqrt{2.25} \quad \text{and} \quad t - 2.5 > -\sqrt{2.25} t2.5<1.5andt2.5>1.5t - 2.5 < 1.5 \quad \text{and} \quad t - 2.5 > -1.5 1<t<41 < t < 4

Answer (e): The height of the ball is greater than 25 m during the time interval 1<t<41 < t < 4 seconds. Accurate to one decimal place: (1.0, 4.0).


Final Answers:

a) 38.5 m
b) 1 m
c) 5 seconds
d) 25 m
e) (1.0, 4.0) seconds


Would you like a detailed explanation of any of the steps?
Here are 5 related questions for further exploration:

  1. How would the equation change if the ball were hit from a higher initial height?
  2. What is the significance of the coefficient 6-6 in the equation?
  3. How would you determine the velocity of the ball at any given time?
  4. What is the total distance traveled by the ball?
  5. Can you express the function in standard quadratic form and find its roots?

Tip: Use graphing tools to visualize parabolas for a better understanding of their behavior!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Parabolas
Inequalities

Formulas

Vertex form of a quadratic function: h(t) = a(t - h)^2 + k
Quadratic equation formula: ax^2 + bx + c = 0
Square root property to solve quadratic equations
Inequalities for finding intervals

Theorems

Properties of parabolas
Vertex theorem for quadratic functions

Suitable Grade Level

Grades 9-11