Answer:
<u>We are given:</u>
initial velocity (u) = 20m/s
acceleration (a) = 4 m/s²
time (t) = 8 seconds
displacement (s) = s m
<u />
<u>Solving for Displacement:</u>
From the seconds equation of motion:
s = ut + 1/2 * at²
replacing the variables
s = 20(8) + 1/2 * (4)*(8)*(8)
s = 160 + 128
s = 288 m
Wow ! This one could have some twists and turns in it.
Fasten your seat belt. It's going to be a boompy ride.
-- The buoyant force is precisely the missing <em>30N</em> .
-- In order to calculate the density of the frewium sample, we need to know
its mass and its volume. Then, density = mass/volume .
-- From the weight of the sample in air, we can closely calculate its mass.
Weight = (mass) x (gravity)
185N = (mass) x (9.81 m/s²)
Mass = (185N) / (9.81 m/s²) = <u>18.858 kilograms of frewium</u>
-- For its volume, we need to calculate the volume of the displaced water.
The buoyant force is equal to the weight of displaced water, and the
density of water is about 1 gram per cm³. So the volume of the
displaced water (in cm³) is the same as the number of grams in it.
The weight of the displaced water is 30N, and weight = (mass) (gravity).
30N = (mass of the displaced water) x (9.81 m/s²)
Mass = (30N) / (9.81 m/s²) = 3.058 kilograms
Volume of displaced water = <u>3,058 cm³</u>
Finally, density of the frewium sample = (mass)/(volume)
Density = (18,858 grams) / (3,058 cm³) = <em>6.167 gm/cm³</em> (rounded)
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I'm thinking that this must be the hard way to do it,
because I noticed that
(weight in air) / (buoyant force) = 185N / 30N = <u>6.1666...</u>
So apparently . . .
(density of a sample) / (density of water) =
(weight of the sample in air) / (buoyant force in water) .
I never knew that, but it's a good factoid to keep in my tool-box.
Answer:
- <u>77.8 m/s, downward</u>
Explanation:
For uniform acceleration motion, the average speed is equal to half the soum of the initial velocity, Vi, and the final velocity, Vf
- Average speed = (Vf + Vi)/2
Also, by definition, the average speed is the distance divided by the time:
- Average speed = distance / time
Then:
Other kinematic equation for uniform acceleration is:
Since the window is falling and the air resistance is ignored, a = g (gravitational acceleration ≈ 9.8m/s²)
Replacing the known values we can set a system of two equations:
From (Vf + Vi)/2 = 300m/6.62s
(Vf + Vi) = 2 × 300m/6.62s
- Vf + Vi = 90.634 equation 1
From Vf = Vi + a×t
Vf - Vi = 9.8 (6.62)
- Vf - Vi = 64.876 equation 2
Adding the two equations:
- Vf = 77.8 m/s downward (velocities must be reported with their directions)
Answer:
When the Earth and sun are perfectly lined up, then it will happen. They can tell when it's going to happen.
Explanation:
This is why it only happens in some places. Some days it's not sunny out, so it's not going to happen.
