SOLUTION: A rock is thrown from the top of a tall building. The distance, d, in feet, between the rock and the ground t seconds after it is thrown is given by the model
d=-16t^2-2t+524
Algebra.Com
Question 312082: A rock is thrown from the top of a tall building. The distance, d, in feet, between the rock and the ground t seconds after it is thrown is given by the model
d=-16t^2-2t+524
How long after the rock is thrown is it 321 feet from the ground?
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
We are given that
So we are at the top of a 524 foot tall building throwing a rock downward with an initial velocity of 2 feet per second toward the ground.
But we want to know the time when
feet.
Set the two expressions equal to each other because they are both equal to 
.
Which is to say:
Just solve the quadratic for 
. Hint: The quadratic factors because 2 times -8 is -16, (-8 times -7) plus (2 times -29)\ = 56 minus 58 = minus 2, and -7 times -29 is 203.
One of the roots is negative -- discard it. You don't care what happened before you threw the rock. The positive root is the number of seconds that will have elapsed when the height of the rock is 321 feet.
John
RELATED QUESTIONS
A rock is thrown from the top of a tall building. The distance D, in feet, between the... (answered by checkley71)
A rock is thrown from the top of a tall building. The distance d, in feet, between the... (answered by josmiceli)
50. A rock is thrown from the top of a tall building. The distance in feet, between the... (answered by checkley75)
A rock is thrown from the top of a tall building. The distance, in feet, between the rock (answered by macston)
A rock is thrown from the top of a tall building. The distance d in feet, between the... (answered by josmiceli)
please help me solve
a rock is thrown from the top of the building . The distance in... (answered by richwmiller)
Problem: A rock is thrown from the top of a tall building. The distance, in feet, between (answered by Alan3354)
Hello! I have a word problem and I have no idea how to solve it, if you could solve it... (answered by Earlsdon)
A rock is thrown from the top of a buliding. The distance, in feet, between the rock and (answered by stanbon)