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Sergeeva-Olga [200]
3 years ago
12

Jack drops a stone from rest off of the top of a bridge that is 24.4 m above the ground. After the stone falls 6.6 m, Jill throw

s a second stone straight down. Both rocks hit the water at the exact same time. What was the initial velocity of Jill's rock? Assume upward is the positive direction and downward is negative. (Indicate the direction with the sign of your answer.)
Physics
1 answer:
alukav5142 [94]3 years ago
4 0
-17.555m/s

first I found the time it took for jacks stone to reach the bottom, using the formula vf = vi + at, vf and vi are final and initial velocities.

then i found the velocity at 6.6m using vf^2 = vi^2 + 2ad
and I found the time it took to get to 6.6m, so that I knew how long Jill waited to throw her stone, I used the formula d = t(vi+vf)/2, then i done total time - the time she waited, to get the time it took for there stones to hit the ground at the same time.

then to find the initial velocity of her throw I used the formula d = vit + (at^2)/2
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Answer:

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As gravity continues to crush the inner core, the fusion of carbon and oxygen begins. What temperature is needed for the fusion
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600,000,000 degree C

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7 0
3 years ago
If an object is projected upward from ground level with an initial velocity of 144144 ft per​ sec, then its height in feet after
Liula [17]

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4.5 s, 324 ft

Explanation:

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The equation that describes its height at time t is

s(t) = -16t^2 + 144 t (1)

where t, the time, is measured in seconds.

In order to find the time it takes for the object to reach the maximum height, we must find an expression for its velocity at time t, which can be found by calculating the derivative of the position, s(t):

v(t) = s'(t) = -32t +144 (2)

At the maximum heigth, the vertical velocity is zero:

v(t) = 0

Substituting into the equation above, we find the corresponding time at which the object reaches the maximum height:

0=-32t+144\\t=\frac{144}{32}=4.5 s

And by substituting this value into eq.(1), we also find the maximum height:

s(t) = -16(4.5)^2+144(4.5)=324 ft

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3 years ago
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