Consider the upward direction of motion as positive and downward direction of motion as negative.
a = acceleration due to gravity in downward direction = - 9.8 
v₀ = initial velocity of rock in upward direction = ?
v = final velocity of rock at the highest point = 0 
t = time to reach the maximum height = 4.2 sec
Using the kinematics equation
v = v₀ + a t
inserting the values
0 = v₀ + (- 9.8) (4.2)
v₀ = 41.2
The normal stress follows the formula written below:
σ = F/A
There are two types of stress, axial and tangential. Since we are only given with the dimension of the radius (and not the length), the possible stress is axial. So, the area is,
A = πr² = π(0.75 in)² = 1.767 in²
So,
σ = F/A = 500 lb/1.767 in² = <em>282.94 psi</em>
The answer is B. the germinal stage
18 mililiter is equivilent to 0.0047551
The evidence that astronomers use to prove jets travel in opposite direction is Spectral lines from a very fast moving ionized gases.
<h3>Who are the astronomers?</h3>
Astronomer is a person who study astronomy which is a scientific study that has to do with space, space bodies, comets, planets, stars and so on.
Therefore, The evidence that astronomers use to prove jets travel in opposite direction is Spectral lines from a very fast moving ionized gases.
Learn more about astronomers below.
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