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A stone is dropped from the upper observation deck of a tower, 50 m above the ground...?
So this is for my assignment, I've done all of it, except this one question that I'm absolutely stumped on.
A stone is dropped from the upper observation deck of a tower, 50 m above the ground. (Assume g = 9.8 m/s^2.)
(a) Find the distance (in meters) of the stone above ground level at time t.
Answer: -4.9t^2 +50
(b) and (c) dont matter and I have done those as well, I'm just confused about part (d)
(d) If the stone is thrown downward with a speed of 8 m/s, how long does it take to reach the ground? (Round your answer to two decimal places.)
Wouldn't I just plug 8 into the velocity equation, so
-8 = -9.8t and then solve for t?
I keep getting it wrong doing it that way though.
1 Answer
- 8 years agoFavorite Answer
For (d) the downward speed is added on to the velocity. So, you will get
v(t)=-9.8t+(-8)
Then integrate into the distance along with the 50m above ground.
s(t)=-4.9t^2 - 8t + 50
Set distance to 0, and solve for t. In this case, you need to use the quadratic equation.
It should be about 2.48 seconds