Question

If an object is dropped from a height of 55 feet, the function d = -16^2 + 55 gives the height of the object after t seconds. Graph this function. Approximately how long does it take the object to reach the ground (d=0)

Answer 1

Approximately 1.9 seconds (correct to nearest tenth)

Explanation:

Looks like the function is d = -16t^2 + 55 ( you left out the t)

The answer is the value of t when d = 0 so we have the equation:-

0 = -16t^2 + 55

16t^2 = 55

t^2 = 55/16

t = sqrt (55/16)

= 1.85 seconds

Answer 2

t is approximately 1.854049622 seconds

Explanation:

d = -16 t^2 + 55

Let d = 0

0 = -16 t^2 + 55

Subtract 55 from each side

-55 = -16 t^2

Divide by -16 on each side

-55/-16 = -16 /-16t^2

55/16 = t^2

Take the square root of each side

sqrt(55/16) = sqrt(t^2)

We only take the positive square root because time must be positive

sqrt(55/16) = t

t is approximately 1.854049622 seconds