# math

posted by .

Your friend is standing below the window outside of our classroom and attempting to throw a rock past the window to get your attention. The rock is thrown straight up in the air and passes our window 0.40s after being released. It passes the same window on its way back down 1.60s later. What was the initial velocity of the rock? Did the height of the
window matter?

• math -

once past the window, the rock spent .8 seconds going up and .8 seconds going down.

So, the rock spent 1.2 seconds going up.

since v = Vo-32t and v(1.2)=0,

Vo-32(1.2)=0
Vo = 38.4

Doesn't matter how high the windows is, though its location is determined by the time intervals indicated.

## Similar Questions

1. ### physics

Bill kicks a rock off the top of his apartment building. It strikes a window across the street 12 m away. The acceleration of gravity is 9.8 m/s2 . If the window is 24 m below the position where Bill contacted the rock, how long was …
2. ### Physics I

Bill kicks a rock off the top of his apartment building. It strikes a window across the street 18m away. The acceleration of gravity is 9.8 m/s sqaured. If the window is 12 m below the position where bill contacted the rock, how long …
3. ### physics

Bill kicks a rock oﬀ the top of his apartment building. It strikes a window across the street 11 m away. The acceleration of gravity is 9.8 m/s 2 . If the window is 22 m below the position where Bill contacted the rock, how …
4. ### physics

Bill kicks a rock oﬀ the top of his apartment building. It strikes a window across the street 12 m away. The acceleration of gravity is 9.8 m/s^2. If the window is 16 m below the position where Bill contacted the rock, how long …
5. ### physics

You drop a rock from rest out of a window on the top floor of a building, 50.0 m above the ground. When the rock has fallen 3.80 m, your friend throws a second rock straight down from the same window. You notice that both rocks reach …
6. ### physics

You drop a rock from rest out of a window on the top floor of a building, 50.0 m above the ground. When the rock has fallen 3.80 m, your friend throws a second rock straight down from the same window. You notice that both rocks reach …
7. ### science

Bill kicks a rock off the top of his apt building it strikes a window across the street 18m away the acceleration of gravity is 9.8m/s if the window is 25m below the position where bill contacted the rock how long was it ini the air
8. ### Physics

Bill kicks a rock off the top of his apartment building. It strikes a window across the street 15m away. The acceleration of gravity is 9.8 m/s^2. If the window is 13m below the position where Bill contacted the rock, how long was …
9. ### Physics

A ball thrown upward from the a point 7 meters below the bottom of a window rises past the window, which is 2.5 meters high, passing the window in 0.33 seconds. How fast was it going when it reached the bottom of the window, and with …
10. ### Physics

You throw a small rock straight up from the edge of a highway bridge that crosses a river. The rock passes you on its way down, 7.00 s after it was thrown. What is the speed of the rock just before it reaches the water 29.0 m below …

More Similar Questions