A smart-phone is thrown upwards from the top of a 448-foot building with an initial velocity of 48 feet per second. The height h of the smart-phone after t seconds is given by the quadratic equation h = − 16 t 2 + 48 t + 448 h=-16t2+48t+448. When will the smart-phone hit the ground?

The smart-phone hit the ground when t = 7 s

Step-by-step explanation:

The height "h" is defined as:

h=16t^2 + 48t + 448

And, when the smart-phone hits the ground, h = 0 ft . Then,

16t^2 + 48t + 448 = 0

And this is a quadratic equation, and we can solve it using the formula for ax^2 + bx + c = 0, which is

x=

So,

t =

t =

And, we have two responses,

t_1 =    and    t_2 =

t_1 = - 4 s              and    t_2 = 7 s

As we know, the time is a quantity that cannot have a negative value, so, we take the result 2.

This variable that is impacted by manipulating the independent variable is known as dependent variable

Step-by-step explanation:

One of the methods to test a hypothesis is the use of independent variable. The independent variable is manipulated to know if the change will be effective or not.

The variable which will be impacted by the independent variable is called dependent variable. The researcher manipulated the values for independent variable to check if the dependent variable changes or not ..