Posted by Anonymous on Wednesday, April 4, 2012 at 10:42pm.
This is really urgent so please please please help.
The height(H) of an object that has been dropped or thrown in the air is given by:
H(t)=4.9t^2+vt+h
t=time in seconds(s)
v=initial velocity in meters per second (m/s)
h=initial height in meters(m)
H=height
h=initial height
Is there a difference but, anyway I didn't make this clear on the last post.
A ball is thrown vertically upwardd from the top of the Leaning Tower of Pisa (height=53m) with an initial velocity of 30m/s. Find the time(s) at which:
a)the ball's height equals the hight of the tower
H(t)=4.9t^2+30t+53
H(t)=???
b)the ball's height is greater than the height of the tower
c)the ball's height is less than the height of the tower
d)the ball reaches its maximum height
I don't know how to do this problem.
Please Help and Thank You very much =)

Math Help (URGENT X10)  Rami Dahabreh, Thursday, April 5, 2012 at 2:15am
acceleration downward due to gravity is 10m/s to be exact 9.8m/s
this is enough to get you to start thinking

Math Help (URGENT X10)  Steve, Thursday, April 5, 2012 at 11:04am
h(t) = 4.9t^2 + 30t + 53
a) ball goes up, comes back down to the top of the tower. So, we want
53 = 4.9t^2 + 30t + 53
0 = 4.9t^2 + 30t
0 = t(4.9t + 30)
so, t=0 (at the start) or t = 6.12 (as it comes back down)
If t(4.9t+30)=0, either
t=0
or
4.9t+30 = 0
That is, t = 6.12
If you can't solve a factored expression, you have some review to do.
b) same calculation but, t is between 0 and 6.12. That is 0 < t < 6.12
c) same calculation, but restricting t to positive values, t>6.12
Naturally, we could also restrict t to the point where height >= 0.
d) vertex of any parabola is where x = b/2a = 30/9.8 = 3.06
you know from the quadratic formula that x = b/2a ± sqrt(blah blah)
Parabolas are symmetric, so the vertex is midway between the roots, which are equally spaced around x = b/2a
h(3.06) = 98.9
Answer This Question
Related Questions
 Math  The height(h) of an object that has been dropped or thrown in the air is ...
 Math  The height(H) of an object that has been dropped or thrown in the air is ...
 Algebra  The height, in meters, of a projectile can be modeled by h= 4.9t^2 + ...
 Math  In physics, one learns that the height of an object thrown upward from an...
 math  An object that is falling or vertically projected into the air has it ...
 Maths  object thrown upward from an initial height of h0 feet with an initial ...
 College Algebre  Here is the math problem: The height of an object in free fall...
 Algebra  A ball is thrown upward with an initial velocity of 14 meters per ...
 math  using this information: if an object is thrown straight up into the air ...
 math  using this information: if an object is thrown straight up into the air ...
More Related Questions