- Download PDF
If an object is thrown vertically upward with an initial velocity of v, from an original position of s, the height h at any time t is given by: h = -16t^2 + vt + s (where h and s are in ft, t is in seconds and v is in ft/sec.)
If a rock is thrown upward from a height of 100 ft, with an initial velocity of 32 ft/sec, sholve for the itme that it takes for it to hit the ground (when h = 0).
Round your answer to 2 decimals.
1 Answer | Add Yours
`h = -16t^2 + vt + s`
s = original position = 100ft
v = 32 ft/sec
h = 0 when it hits ground
Solve for t.
`0 = -16t^2 + 32t + 100`
`0 = (-32+-sqrt(32^2 - 4(-16)(100)))/(2(-16))`
`0 = (-32+-sqrt(7424))/-32`
`0 = -1.6925and 3.6925`
Since time is not negative, -1.6925 is an extraneous solution, therefore it takes 3.69 seconds for the object to hit the ground.
We’ve answered 324,174 questions. We can answer yours, too.Ask a question