Question

Which equation would best help solve the following problem:



Gary kicks a field goal with an initial vertical velocity of 38 meters per second. How long will it take the football to hit the ground?









A.

–16t2+ 38t = 0








B.

16t2 + 38t = 0








C.

–4.9t2 + 38t = 0








D.

–4.9t2 – 38t = 0

@aaronq D?

Answer 1

I'll make your E nice and flat ;)... I'm pretty sure I made this joke already though...

Answer 2

It's pretty much the same thing,

\(\sf y_f=y_i+v_y\Delta t +\dfrac{1}{2}a_y(\Delta t)^2\)

the acceleration is due to gravity so it's

\(\sf y_f=y_i+(38~m/s)\Delta t +\dfrac{1}{2}(-9.8~m/s^2)(\Delta t)^2\)

Answer 3

so it'd not D, it's C. recall that gravity would have a negative value and the initial velocity a positive one.

Answer 4

Oh! alright, I see where I messed up. thank you again

Answer 5

signs are easy to mess up, keep an eye out. no problem

Answer 6

Cough cough... this belongs in the physics section.

Answer 7

nope, this is math. Projectile Motion

Answer 8

That equation is derived from a situation involving classical mech. This is physics heh, esp since it's applied. Math is just the language of Physics.