A small rock falling from the top of a 124-ft-tall building with an initial downward velocity of - 30 ft/sec is modeled by the equation h (t) = - 16t2 - 30t + 124, where t is the time in seconds. For which interval of time does the rock remain in the air?

A) t = 2

B) t > - 2

C) t < 2

D) t > 2

Question

Physics

Hayden Blackwell

25 December, 18:13

A small rock falling from the top of a 124-ft-tall building with an initial downward velocity of - 30 ft/sec is modeled by the equation h (t) = - 16t2 - 30t + 124, where t is the time in seconds. For which interval of time does the rock remain in the air?

A) t = 2

B) t > - 2

C) t < 2

D) t > 2

+1

Answers (1)

Know the Answer?

Haylee Zavala · Answer 1

We first equate the height to 0 to find the time when the rock hits the ground. The quadratic equation formed:

16t² + 30t - 124 = 0

Solving,

t = 2 and t = - 3.875 (neglected)

The stone reaches the ground at t = 2 so it is in the air before that.

C is the answer.

A small rock falling from the top of a 124-ft-tall building with an initial downward velocity of - 30 ft/sec is modeled by the equation h (t) = - 16t2 - 30t + 124, where t is the time in seconds. For which interval of time does the rock remain in the air?A) t = 2B) t > - 2C) t < 2D) t > 2

A small rock falling from the top of a 124-ft-tall building with an initial downward velocity of - 30 ft/sec is modeled by the equation h (t) = - 16t2 - 30t + 124, where t is the time in seconds. For which interval of time does the rock remain in the air?

A) t = 2

B) t > - 2

C) t < 2

D) t > 2