13.An airplane starts from rest at the end of a runway and accelerates at a constant rate. In the first second, the airplane travels 1.11 m. How much additional distance will the airplane travel during the second second of its motion?

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Answer:

The answer is 3.33m

Explanation:

The acceleration "a" is constant.

Acceleration is the variation of velocity over time,

[tex]\frac{dv}{dt} = a[/tex].

solving the last equation

[tex]\int_{v_0}^v dv = a\int_0^t dt \rightarrow v-v_0 = at[/tex],

where [tex]v_0=0[/tex] because the airplane starts from rest.

Once again, velocity is the variation of distance over time.

[tex]\frac{dx}{dt} = at \rightarrow \int_{x_0}^x dx = a\int_0^t t\ dt[/tex]

then

[tex]x- x_0 = \frac{1}{2}at^2[/tex]

where [tex]x_0=0[/tex] if we consider  the end of the runway as the initial point (this step is for simplicity but you can let it expressed, it's going to cancel anyway).

If [tex]x=1.11\ m[/tex] at [tex]t=1s[/tex], then

[tex]a = \frac{2x}{t^2} = 2.22\ m/s^2[/tex]

and the final expression for the distance is

[tex]x = 1.11 t^2[/tex].

If t = 2s, x = 4.44 m. Which means thad the additional distance is

[tex]x(2s) - x(1s) = 4.44 - 1.11 = 3.33\ m[/tex]