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Justin and Elena each launched a toy rocket into the air. The height of Justin's rocket is modeled by the equation

[tex]\[ h(t) = -16t^2 + 60t + 2 \][/tex]

Elena launched her rocket from the same position, but with an initial velocity double that of Justin's. Which equation best models the height of Elena's rocket?

A. [tex]\[ h(t) = -16t^2 + 120t + 2 \][/tex]
B. [tex]\[ h(t) = -32t^2 + 120t + 4 \][/tex]
C. [tex]\[ h(t) = -32t^2 + 60t + 2 \][/tex]
D. [tex]\[ h(t) = -16t^2 + 60t + 4 \][/tex]


Sagot :

To determine which equation best models the height of Elena's rocket, let's analyze the details given in the problem:

1. Justin's Rocket Equation:
Justin's rocket's height is given by the equation
[tex]\[ h = -16t^2 + 60t + 2 \][/tex]
where [tex]\( h \)[/tex] is the height of the rocket at time [tex]\( t \)[/tex], the coefficient of [tex]\( t^2 \)[/tex] represents the effect of gravity, the coefficient of [tex]\( t \)[/tex] represents the initial velocity, and the constant term represents the initial height.

2. Elena's Initial Velocity:
- The problem states that Elena's rocket is launched with an initial velocity that is double that of Justin's.
- Justin's initial velocity is 60 (the coefficient of [tex]\( t \)[/tex]).
- Therefore, Elena's initial velocity would be [tex]\( 2 \times 60 = 120 \)[/tex].

3. Equation Components:
- The coefficient of [tex]\( t^2 \)[/tex] (the effect of gravity) should remain the same at -16.
- The new initial velocity (coefficient of [tex]\( t \)[/tex]) should be 120.
- The initial height remains unchanged at 2.

Given these components, we can construct the equation for the height of Elena's rocket:
[tex]\[ h = -16t^2 + 120t + 2 \][/tex]

Now, let's match this derived equation with the given options:

- Option 1: [tex]\( h = -16t^2 + 60t + 4 \)[/tex]
- Option 2: [tex]\( h = -32t^2 + 120t + 4 \)[/tex]
- Option 3: [tex]\( h = -32t^2 + 60t + 2 \)[/tex]
- Option 4: [tex]\( h = -16t^2 + 120t + 2 \)[/tex]

The equation that matches our derived one, [tex]\(-16t^2 + 120t + 2\)[/tex], is Option 4.

Thus, the equation that best models the height of Elena's rocket is:
[tex]\[ \boxed{h = -16t^2 + 120t + 2} \][/tex]