Answer:
4.41 × 10¹² J, 2.72 × 10³ m³, 0.907 × 10 ⁻³ m
Explanation:
Gravitational potential energy = mgh
where m is mass in kg, g is acceleration due to gravity in m/s², and h is the distance from the base of the dam.
mass of the surface water = density of water × volume of water × 1 m = 1000 kg / m³ × 3.0 × 10⁶ m² × 1 m = 3 × 10⁹ kg
Gravitational potential energy = 3 × 10⁹ kg × 9.81 m/s² × 150 m = 4.41 × 10¹² J
b)what volume of water must pass through the dam to produce 1000 kw-hrs
1 000 kw-hr = 3.6 × 10 ⁹ J
the dam has mechanical energy conversion of 90% to electrical energy
Gravitational potential energy needed = 3.6 × 10 ⁹ J / 0.9 = 4 × 10⁹ J
mass of water needed = Energy required / g h = 4 × 10⁹ J / (9.81 m/s² × 150 m) = 2.718 × 10 ⁶ kg
density = mass / volume
volume = mass / density = 2.718 × 10 ⁶ kg / (1000 kg/ m³) = 2.72 × 10³ m³
the distance the level of the water in the lake fell = volume / area = 2.72 × 10³ m³ / (3.0×10⁶ m²) = 0.907 × 10 ⁻³ m
In order to answer this question ... strange as it may seem ...
we only need one of those measurements that you gave us
that describe the door.
The door is hanging on frictionless hinges, and there's a torque
being applied to it that's trying to close it. All we need to do is apply
an equal torque in the opposite direction, and the door doesn't move.
Obviously, in order for our force to have the most effect, we want
to hold the door at the outer edge, farthest from the hinges. That
distance from the hinges is the width of the door ... 0.89 m.
We need to come up with 4.9 N-m of torque,
applied against the mechanical door-closer.
Torque is (force) x (distance from the hinge).
4.9 N-m = (force) x (0.89 m)
Divide each side by 0.89m: Force = (4.9 N-m) / (0.89 m)
= 5.506 N .
<u>Answer:</u>
Mass of base ball 
<u>Explanation:</u>
Circumference of baseball = 2πr = 23 cm
So radius of baseball = 3.66 cm = 
m
Mass per unit volume of baseball = Mass per unit volume of neutron or proton.
Mass of proton = 
kg
Diameter of proton = 
m
Radius of proton = 
m
Volume of ball = 
Now substituting all values in Mass per unit volume of baseball = Mass per unit volume of neutron or proton.
So mass of base ball
I know you're probably done with this by now, but the answer is *Lake-Effect Snow*
The density of the substance is the ratio of its mass over the space it occupies. In mathematical equation, this can be expressed as,
ρ = m / v
where ρ is density, m is mass, and v is volume.
Substituting the known values from the given,
ρ = (45 g) / (8 cm³)
ρ = 5.625 g/cm³
<em>ANSWER: 5.625 g/cm³</em>
