You are here:

- Home
- Science
- Math for Kids
- Algebra
- algebra 2

Advertisement

Emilee and Charles shoot a rocket into the air during Mr. Jones' physics class at an initial velocity of 128 ft/sec. Use the equation of h = vt - 16(t squared) to find the maximum height, total time in the air, and how long it takes to land?

Assuming the 128 ft/sec is vertical (i.e. straight up), then...

h(t)=128t-16t^2 gives the equation of motion in the vertical direction

(i.e. the height above the ground). Since this is a parabola, we know the

vertex (i.e. turning point) occurs on its axis of symmetry, t=-b/(2a)=-128/(2*(-16)) sec

==> t= -128/-32 sec = 4 sec.

Thus, h_max=128*4-16*4^2 ft = 512-256 ft = 256 ft, at t=4 sec.

It will hit the ground after another 4 sec. (when h=0 again after t=0),

hitting the ground after 8 sec.

OK?

A. Mantell

- Add to this Answer
- Ask a Question

Rating(1-10) | Knowledgeability = 10 | Clarity of Response = 10 | Politeness = 10 |

Comment | Very wordy! Would have just liked the problem worked out. |

Algebra

Answers by Expert:

Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!

Over 15 years teaching at the college level.**Organizations**

NCTM, NYSMATYC, AMATYC, MAA, NYSUT, AFT.**Education/Credentials**

B.S. in Mathematics from Rensselaer Polytechnic Institute

M.S. (and A.B.D.) in Applied Mathematics from SUNY @ Stony Brook