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musickatia [10]
3 years ago
10

You are visiting your friend Fabio's house. You find that, as a joke, he filled his swimming pool with Kool-Aid, which dissolved

perfectly into the water. However, now that you want to swim, you must remove all of the Kool-Aid contaminated water. The swimming pool is round, with a 9 foot radius. It is 8 feet tall and has 7.5 feet of water in it. How much work is required to remove all of the water by pumping it over the side? Use the physical definition of work, and the fact that the density of the Kool-Aid contaminated water is σ=63.5lbs/ft3
Physics
2 answers:
oksian1 [2.3K]3 years ago
3 0

Answer:

Explanation:

The volume of contaminated water

= cross sectional area x height of water level

3.14 x 9 x 9 x 7.5 ft³

= 1907.55 ft³

mass = density x volume

= 1907.55 x 63.5 lbs

m = 121129.425 lbs

This mass has to be raised to the height of 8 ft before evacuation .

There is a rise of centre of mass of

8 - 7.5/2 ft

h = 4.25 ft

Energy required

= mgh

= 121129.425 x 32 x 4.25

= 16473601.8 unit.

skelet666 [1.2K]3 years ago
3 0

Answer:

Workdone= 8.08×10^3Joules

Explanation:

dV= pir^2 dx

dV = pi×9^2 = 81pi

dF= density× pi× r^2 dx

dF= 63.5 × 81pi dx= 5143.5pi dx

W= Integral from7.5ft of water in the pool(8 -×)dx

W= 5143.5pi(8-7.5)

W= 5143.5 × 3.142 × 0.5

W= 8080.44Joules = 8.08×10^3Joules

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A stream moving with a speed of 7.1 m/s reaches a point where the cross-sectional area of the stream decreases to one half of th
lana66690 [7]

Answer:

14.2 m/s

Explanation:

Given data:

Speed of the stream, v₁ = 7.1 m/s

let the cross section area at initial point be A₁

now area at the second point, A₂ = (1/2)A₁ = 0.5A₁

now, from the continuity equation, we have

A₁v₁ = A₂v₂

where, v₂ is the velocity at the narrowed portion

thus, on substituting the values, we get

A₁ × 7.1 = 0.5A₁ × v₂

or

v₂ = 14.2 m/s

8 0
3 years ago
A physics student stands on a cliff overlooking a lake and decides to throw a softball to her friends in the water below. She th
aliina [53]

Answer:

58.5 m

Explanation:

First of all, we need to find the total time the ball takes to reach the water. This can be done by looking at the vertical motion only.

The initial vertical velocity of the ball is

u_y = u sin \theta

where

u = 21.5 m/s is the initial speed

\theta=33.5^{\circ} is the angle

Substituting,

u_y = (21.5) sin 33.5^{\circ} =11.9 m/s

The vertical position of the ball at time t is given by

y = h + u_y t + \frac{1}{2}gt^2

where

h = 13.5 m is the initial heigth

g = -9.8 m/s^2 is the acceleration of gravity (negative sign because it points downward)

The ball reaches the water when y = 0, so

0 = h + u_yt +\frac{1}{2}gt^2\\0 = 13.5 +11.9 t - 4.9t^2

Which gives two solutions: t = 3.27 s and t = -0.84 s. We discard the negative solution since it is meaningless.

The horizontal velocity of the ball is

u_y = u cos \theta = (21.5) cos 33.5^{\circ} =17.9 m/s

And since the motion along the horizontal direction is a uniform motion, we can find the horizontal distance travelled by the ball as follows:

d= u_x t = (17.9)(3.27)=58.5 m

3 0
2 years ago
A wave with a frequency of 32 Hz has a wavelength of 9 meters. At what speed will this
jarptica [38.1K]

Answer:

228 m/s

Explanation:

f = 32 Hz

λ = 9 m

v = ?

v = f λ

v = (32 Hz) (9 m)

v = 288 m/s

6 0
3 years ago
Select the correct answer. Which chemical reaction absorbs energy? A. photosynthesis B. explosion C. current produced by a batte
zavuch27 [327]

Answer:

Explanation:

Photosynthesis

4 0
3 years ago
Read 2 more answers
Explain why, in terms of forces, there is a risk of head injury when diving from this height. Suggest why the high divers would
podryga [215]

Answer:

Due to lower risk of injury or damage.

Explanation:

The high divers would choose to enter the water from the feet first because there is low risk of injury. The brain is the most important part of the body which very sensitive to any small injury. Small injury to brain leads to big problems in life. High divers can reach speeds of nearly 60 mph and enters about 28m into the water in about three seconds which can damage the head region if comes in contact with the ground so this is the reason the high divers avoid of entering in the water through their heads and choose entering through their feet.

4 0
3 years ago
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