### Home > APCALC > Chapter 12 > Lesson 12.3.1 > Problem 12-92

12-92.

A projectile is launched from the ground at a seconds is given by

*. Its horizontal displacement in feet is given by*

*.*

Write the velocity vector as a function of

.Calculate the magnitude of the velocity vector at

and at the moment when the projectile hits the ground. Make a conjecture about the speed with which projectiles returns to earth.To determine when the projectile hits the ground, solve

. The velocity vector when

is:Sketch this vector and use the Pythagorean Theorem to determine its magnitude.