Wednesday

January 28, 2015

January 28, 2015

Posted by **Julia** on Thursday, December 8, 2011 at 9:24pm.

Find the time when the projectile has returned to the initial height launch, find the time the projectile hits the ground, find the time when the projectile hits the ground when its velocity is 0, find the height of the projectile above ground after 1 second

- Algebra II -
**Damon**, Thursday, December 8, 2011 at 9:42pmg = -9.8 m/s^2

v = +20 - 9.8 t

y = 10 + 20 t -4.9 t^2

a) when is y = 10 again?

10 = 10 + 20 t -4.9 t^2

t(4.9 t-20) = 0

t = 20/4.9 = 4.08 seconds

b) when is y = 0 ?

4.9 t^2 - 20 t - 10 = 0

t = [20 +/- sqrt (400+196)] / 9.8

forget negative time, that was before we started, use + sign

t = 4.53 seconds

c) velocity is 0 at the op when

0 = 20 -9.8 t

t = 2.04 seconds

d) y = 10 + 20 (1) -4.9 (1)^2

= 25.1 meters

**Answer this Question**

**Related Questions**

physics - a projectile is fired from the top of a building with an initial ...

PHYSICS - A Projectile IS FIRED FROM THE TOP OF A BUILDING WITH AN INITIAL ...

intermediate algebra - A projectile is launched directly upward from the top of ...

College Algebra - A projectile is thrown upward with an initial velocity of 272 ...

college algebra - The height of a projectile fired upward is given by the ...

math-algebra - A launched rocket has an altitude, in meters, given by the ...

Algebra~Scary problem! - A launched rocket has an altitude, in meters, given by ...

Physics- i need to know how to do these problems - Two projectiles are launched ...

math - If a projectile is launched from a platform 30 feet high with an initial ...

Math000 - The height (in meters) of a projectile shot vertically upward from a ...