Question

A child shot a toy rocket into the air from their playhouse which stood 5 ft above the ground. The rocket rose to 50 ft above the ground and landed on the ground 3.4 seconds later. The path of the toy rocket could be modeled by a quadratic function, , where h is the height of the toy rocket in feet after t seconds. ⦁ What is the practical domain of the function? ⦁ What is the practical range of the function? ⦁ How would the theoretical domain and range of the function differ from the practical domain and range of the situation?

Answer 1

a. 0 ≤ t ≤ 3.4 s. b. 0 ≤ y ≤ 50 ft. c. i. -∞ ≤ t ≤ +∞. ii. -∞ ≤ y ≤ 50

Explanation:

a. What is the practical domain of the function?

Since the toy rocket lands on the ground 3.4 seconds later, if the time it starts to fly in the air is time t = 0 and the time it lands is time t = 3.4 s, the practical domain of the function is 0 ≤ t ≤ 3.4 s.

b. What is the practical range of the function?

Since the rocket reaches a maximum height of 50 ft, if the maximum height of the toy rocket is y = 50 ft and it lands on the ground at y = 0, the practical range of the function is 0 ≤ y ≤ 50 ft.

c. How would the theoretical domain and range of the function differ from the practical domain and range of the situation?

i. The theoretical values of t is from is from t = -∞ to t = +∞. So, the theoretical domain is -∞ ≤ t ≤ +∞.

ii. Since the maximum value of the function is y = 50, and it also decreases to y = -∞. So, the theoretical domain is from y = -∞ to y = 50. So, the theoretical range is -∞ ≤ y ≤ 50