Question

If a stone is tossed from the top of a 310 meter building, the height of the stone as a function of time is given by h(t) = -9.8t2 – 10t + 310, where t is in seconds, and height is in meters. After how many seconds will the stone hit the ground? Round to the nearest hundredth’s place; include units in your answer. (Points : 20)

Answer 1

first make h(t) =0 since the height is zero when it hits the ground
\[-9.8t^2-10t+310=0\]
now solve using the quadratic formula
\[t= \frac{b \pm \sqrt{b^2-4ac}}{2a}\]
you will get a positive root and a negative one,
since the time has to be positive, u neglect the negative

Answer 2

a=-9.8
b=-10
c=310

Answer 3

t = -6.15
t = 5.137

Neglect the negative answer. Your answer is:
The rock will take 5.137 seconds to hit the ground.