A projectile is fired upward from the ground with an initial velocity of 300 feet per second.

Question

A projectile is fired upward from the ground with an initial velocity of 300 feet per second. Neglecting air resistance, the height of the projectile at any time t can be described by the polynomial function P(t) = ­16t2 + 300t  

a. What is the height of the projectile when t = 1 second. 284 feet?

b. What is the height of the projectile when t = 5 seconds?

c. How long will it be until the object hits the ground?  

Answer 1

Aisha, I will make one change to the equation you typed in:

P(t) = -16t² + 300t the (-16) tells you that the parabola is "upside down" and also fits with Earth's gravity, measured in feet² per second

a) if t = 1, then P(1) = -16*(1²) + 300*1 = 284 feet

b) if t = 5, the P(5) = -16*(5²) + 300*5

c) now we want P(t) to equal zero, so you have to solve the quadratic--for harder problems, you must complete the square or use the quadratic formula

Hope this helps--Andrew

Answer 2

As a math and physics teacher, I can tell you that the polynomial function does not make any sense. According to the function, the projectile will leave the Earth very soon, because it describes accelerated motion, but not decelerated, as in your case when initial velocity of the projectile directed up. Please verify the sign near t² term.

And the last. projectile does not have any height. Projectile can only be some distance from the Earth's surface.

Please, dear students, use common sense before stating the problem and demanding answers.