Question

A toy car launched into the air has a height (h feet) at any given time (t second) as h= -16t + 160t until it hits the ground. At what times is it at a height of 9 feet above the ground?

Answer 1

Answer:

$t_{1} \approx 9.943\,s$ and $t_{2} \approx 0.057\,s$

Step-by-step explanation:

The following polynomial is needed to be solved:

$-16\cdot t^{2} + 160\cdot t - 9 = 0$

The roots are found by means of the General Equation for Second-Order Polynomials:

$t_{1} \approx 9.943\,s$ and $t_{2} \approx 0.057\,s$

Physically speaking, both solutions are reasonable.

Answer 2

Answer:

t = 0.0625

Step-by-step explanation:

Given that,

Height, h = -16t + 160t

To obtain time,t at height,h = 9feet

We substitute h = 9 into the given equation to have:

9 = - 16t + 160t

: 9 = 144t

t = 9/ 144 = 0.0625