SOLUTION: If an object is propelled upward from ground level with an intial velocity of 64 ft. per sec, its height h in feet t seconds later is:
h=-16t^2 = 64t
(a) After how many seconds i
Algebra.Com
Question 336792: If an object is propelled upward from ground level with an intial velocity of 64 ft. per sec, its height h in feet t seconds later is:
h=-16t^2 = 64t
(a) After how many seconds is the height 48 ft?
(b) The object reaches its maximum height 2 sec after it is propelled. What is this maximum height?
(c) After how many seconds does the object hit the ground?
I have read all of the examples that they give me in my math book, but i still have a hard time trying to understand these problems.
Found 2 solutions by stanbon, nyc_function:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
If an object is propelled upward from ground level with an intial velocity of 64 ft. per sec, its height h in feet t seconds later is:
h=-16t^2 + 64t
(a) After how many seconds is the height 48 ft?
Let h=48 and solve for "t":
-16t^2+64t-48 = 0
-16(t^2-4t+3) = 0
(t-3)(t-1) = -
t= 1 sec or t = 3 sec
---------
Ans: time = 1 sec on the way up and time = 3 sec on the way down.
=====================================================================
(b) The object reaches its maximum height 2 sec after it is propelled. What is this maximum height?
f(x) = -16t^2+64t
f(2) = -16(4)+64(2) = 64 ft.
--------------------------------------
(c) After how many seconds does the object hit the ground?
Let h = 0 and solve for "t":
-16t^2+64t = 0
-16t(t-4) = 0
t = 0 or t = 4 seconds
t = 0 seconds refers to the time at which the object is launched.
t = 4 seconds refers to the time at which the object is back on the ground.
======================
Cheers,
Stan H.
Answer by nyc_function(2741) (Show Source): You can put this solution on YOUR website!
Actually, I think you meant
h = -16t^2 + 64t since initial velocity is upward.
a] 48 = -16t^2 + 64t... use the quadratic formula
b] h(2)
c] -16t^2 + 64t = 0 will have two roots, one for t=0 or launch, and the other when it hits the ground.
RELATED QUESTIONS
this is the problem
If an object is propelled upward from the ground level with an... (answered by ankor@dixie-net.com)
I'm having difficulty with this problem: If an object is propelled upward from the ground (answered by jim_thompson5910)
If an object is propelled upward from ground level with an initial velocity of 224 feet... (answered by stanbon)
If an object is propelled upward from ground level with an initial velocity of 224 feet... (answered by solver91311)
If an object is propelled upward from ground level with an initial velocity of 224 feet... (answered by Alan3354)
If an object is propelled upward from ground level with an initial velocity of 224 feet... (answered by drk)
If an object is propelled upward from ground level with an initial velocity of 92.5 feet... (answered by dabanfield)
If an object is propelled upward from ground level with an initial velocity of 224 feet... (answered by Alan3354)
If an object is propelled upward from ground level with an initial velocity of 224 feet... (answered by Alan3354)