Question

A ball is dropped from the top of a 349 footbuilding.How many seconds will it take to hit the ground if the height is given by h=−16t^2+s ,where s is the initial height?

Answer 1

h = −16t^2 + s
Where s is initial height and that is 349 (given). So,
h = -16t^2 + 349

You wanna find out when it will hit the ground, and that will happen when the final height h is zero. So, we plug it in.

0 = -16t^2 + 349

Do you know how to solve this or do you need help?

Answer 2

help please

Answer 3

The quadratic formula lets you solve for the variable in equations that look like: 0 = ax² + bx + c where a, b, and c are constants. All you need to do is identify the a, b, and c, plug it in, and the formula will tell you what the variable can equal (0, 1, or 2 possible answers). You determine which constant is a, b, and c by looking at what it's being multiplied to. a is multiplied to the squared term, b to the x of degree 1 (to first power, no exponent written), and c is just alone.

In this case, 0 = -16t^2 + 349, a = -16 and c = 349, but b is nowhere to be found. You can imagine a generic 0t being added in there though, so b = 0. Then just apply the quadratic formula and solve for t. Using an online calculator, I found t to be 4.67 or -4.67. However, given the context of this problem (only positive time is allowed), the answer must be 4.67.

It takes approx 4.67 seconds for the ball to fall.