The pep squad at the local college basketball game launches T-shirts into the crowd using a cannon that is placed on the floor and stands 2 feet high. The cannon fires shirts with an upward velocity of 38 feet per second. Using the function h=−16t2+38t

, which of the following correctly identifies the intercepts and the vertex and correctly explains the path of the shirts?(1 point)
Responses

(1.19,24.56)
and (2.38,0)
; After being launched from the ground, the shirts will return to ground level after 2.38
seconds.
left parenthesis 1.19 comma 22.56 right parenthesis and left parenthesis 2.38 comma 0 right parenthesis ; After being launched from the ground, the shirts will return to ground level after 2 point 3 8 seconds.

(0,2)
, (1.19,24.56)
, and (2.38,0)
; After being launched from the cannon at a height of 2 feet, the shirts reach the height of 24.56
feet after 1.19
seconds before returning to ground level after 2.38
seconds.
open paren 0 comma 2 close paren, open paren 1 point 1 9 comma 24 point 5 6 close paren, and open paren 2 point 3 8 comma 0 close paren; After being launched from the cannon at a height of 2 feet, the shirts reach the height of 24 point 5 6 feet after 1 point 1 9 seconds before returning to ground level after 2 point 3 8 seconds.

(2.38,0)
; After being launched from the ground, the shirts will return to ground level after 2.38
seconds.
left parenthesis 2.38 comma 0 right parenthesis ; After being launched from the ground, the shirts will return to ground level after 2 point 3 8 seconds.

(0,0)
(1.19,22.56)
and (0,2.38)
; After being launched from the ground, the shirts will reach a height of 1.19
feet in 24.56
seconds before returning to ground level after 2.38
seconds.

1 answer

To analyze the problem and find the intercepts, vertex, and path of the shirts, we'll start with the provided equation for height \( h(t) = -16t^2 + 38t + 2 \), where the initial height of the cannon is 2 feet.

  1. Finding the intercepts:

    • The vertical intercept ( h-intercept ) is when \( t=0 \): \[ h(0) = -16(0)^2 + 38(0) + 2 = 2 \] So, the intercept is \( (0, 2) \).

    • To find the other intercepts (x-intercepts), set \( h(t) = 0 \): \[ -16t^2 + 38t + 2 = 0 \] Using the quadratic formula \( t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \): \[ t = \frac{-38 \pm \sqrt{38^2 - 4 \cdot (-16) \cdot 2}}{2 \cdot (-16)} = \frac{-38 \pm \sqrt{1444 + 128}}{-32} = \frac{-38 \pm \sqrt{1572}}{-32} \] Calculating this gives us two values. The relevant positive root is \( t \approx 2.38 \) seconds.

  2. Finding the vertex:

    • The time to reach the maximum height (vertex) occurs at \( t = -\frac{b}{2a} \): \[ t = -\frac{38}{2 \cdot -16} = \frac{38}{32} = 1.19 \text{ seconds} \]
    • Now, substituting \( t=1.19 \) to find the maximum height: \[ h(1.19) = -16(1.19)^2 + 38(1.19) + 2 \approx 24.56 \text{ feet} \]
    • Thus, the vertex is \( (1.19, 24.56) \).
  3. Path of the shirts: After being launched from the cannon at a height of 2 feet, the shirts reach a maximum height of approximately 24.56 feet after about 1.19 seconds before returning to ground level at 2.38 seconds.

Conclusion: The correct response from the options provided is:

(0,2), (1.19,24.56), and (2.38,0); After being launched from the cannon at a height of 2 feet, the shirts reach the height of 24.56 feet after 1.19 seconds before returning to ground level after 2.38 seconds.