Friday

August 29, 2014

August 29, 2014

Posted by **jhon avendano** on Wednesday, October 24, 2012 at 10:08am.

A) find an equation that models the height of the rock t seconds after it is launched.

b) what is the maximum height of the rock and when will it reach it. explain how you found this answer or show work.

c)when will the rock hit the ground? explain how you found this answer or show work.

d) what is the rock's vertical velocity when it hits the ground? show work

- pre-cal -
**Jennifer**, Wednesday, October 24, 2012 at 10:19amThe initial velocity is in the y-direction.

A) It's height above ground is

y = x0 + v0*t - 1/2*g*t^2

where y is its height, x0 is its initial position, v0 is it's initial speed in the y direction, g is the acceleration due to gravity and t is time. Plugging in the values from the problem:

y = 6 + 170*t -1/2*g*t^2

b) The maximum height will be found at the point when dy/dt equals zero

dy/dt = 170 - 1/2*g*t^2 = 0

Solve for t, then plug this value back into y to find the maximum height

c) The rock will hit the ground when y = 0

0 = 6 + 170*t -1/2*g*t^2

Solve for t using the quadratic equation solutions

d) the velocity is dy/dt = 170 - 1/2*g*t^2

Plug your answer for t from part c into this equation to find the velocity when it hits the ground

**Related Questions**

physics - Julie throws a rock vertically upward. From a height of 64.0 meters ...

algebra - An object that is projected straight downward with initial velocity v ...

algebra - An object that is projected straight downward with initial velocity v ...

math - a rock is thrown straight up in the air from an initial height of ho, in...

Pre-Ap Physics - A rock is projected from the edge of the top of a building with...

Physics - A boy stands on the edge of a building 7 meters high and throws a rock...

Math - A ball is tossed straight upward with an initial velocity of 80 ft per ...

Physics - A projectile is fired with an initial speed of 31.0 at an angle of 10....

Physics - A projectile is fired with an initial speed of 28.0 m/s at an angle of...

physics - A rock is dropped from a treetop 19.6 m high, and then, 1.00 s later, ...