The projectile has a height <em>h</em> at time <em>t</em> given by
<em>h</em> = (14.0 m/s) <em>t</em> - 1/2 <em>g t</em> ²
where <em>g</em> = 9.80 m/s² is the magnitude of the acceleration due to gravity. Solve for <em>t</em> when <em>h</em> = 0 :
0 = (14.0 m/s) <em>t</em> - 1/2 <em>g t</em> ²
0 = 1/2 <em>t</em> (28.0 m/s - <em>g t</em> )
1/2 <em>t</em> = 0 <u>or</u> 28.0 m/s - <em>g</em> <em>t</em> = 0
The first equation says <em>t</em> = 0, which refers to the moment the gun is first fired, so we ignore that solution. We're left with
28.0 m/s - <em>g t</em> = 0
<em>t</em> = (28.0 m/s) / <em>g</em>
<em>t</em> = (28.0 m/s) / (9.80 m/s²)
<em>t</em> ≈ 2.86 s
Do not use water on chemical fires such as magnesium, or on electrical fires.
It will act upon a buoyant force on the magnitude of which is equal to weight of the fluid
Here we know that
now from kinematics we have
now from above all values we have
so final angular speed is -12.6 rad/s
If a man's mass is 80 kg, then ...
-- He weighs 258 newtons on Mars.
-- He weighs 785 newtons (about 176.4 pounds) on Earth.
-- He weighs 130 newtons on the Moon.
-- He weighs different amounts in other different places.
His mass doesn't change. It's 80 kg no matter where he goes.