A rock is thrown from the top of a building . The height, h, of the rock t seconds after it thrown is given by h(t) = - 16t ^ 2 - 2t + 240 . How long will it take the rock to reach a height of 180 feet?

1.875 sec

Step-by-step explanation:

Let h(t) = 180

180 = -16t^2 - 2t + 240

16t^2 + 2t - 60 = 0

2(8t^2 + t - 30) = 0

2(t + 2)(8t - 15) = 0

t = -2  or t = 15/8= 1.875 sec

Note:  time cannot be negative, so -2 is disregarded

the answer is: d) o, f, and kr.

atomic radius of bromine (br) is 114 pm.

atomic radius of oxygen (o) is 73 pm.

atomic radius of fluorine (f) is 72 pm.

atomic radius of krypron (kr) is 112 pm.

the atomic radius of a chemical element is a measure of the size of its atom.

the atomic radius varies with increasing atomic number, but usually increases because of increasing of number of electrons.

the atomic radius decreases across the periods because an increasing number of protons, because greater attraction between the protons and electrons.

step-by-step explanation:

d would equal 12