A football is kicked from the ground at 39.5m/s at an angle of 40.0degrees above the horizontal. At what two times does it reach an altitude of 12.0m

Question

jdoe0001 · Answer

hmmm is there an equation you're meant to use?

anonymous · Answer

this is physics. he's supposed to use known equations.

what exactly is you issue with the problem? @apink<3 ?

anonymous · Answer

its projectiles and the equations are basically the big 4 and v = d/t

anonymous · Answer

im suppose to find the two times of the ball at a altitude of 12m
so basically the time up and down

anonymous · Answer

Use:

$$\Delta s = V_0 t + \frac{ 1 }{ 2 }at^2$$

since the forces/accelerations in the x and y directions are independent, and we only care about the y direction, we use this equation for the y direction:
$$\Delta y = V_0  (\sin  \theta )t + \frac{ 1 }{ 2 } g t^2$$

solving for t as you would a polynomial (quadratic eqn)