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Contact [7]
3 years ago
14

A rigid dam is composed of material of SG = 5 . The dam height is 20 m . What is the minimum thickness b of the dam necessary to

prevent it from tipping about the point O when the water reaches the top of the dam considering unit width? Assume that the maximum hydrostatic pressure acts over the bottom of the dam.
Physics
1 answer:
Kay [80]3 years ago
3 0

Answer:

b = 5.164 m is the minimum thickness of the dam

Explanation:

Given

SG = 5

h = 20 m

b = ?

w = 1 m

γw = 9800 N/m³

We  can get the forces as follows

Fp =  γw*(h/2)*(h*w)

⇒ Fp = (9800 N/m³)*(20 m/2)*(20 m*1 m) = 1.96*10⁶N

W = (SG*γw)*(h*b*w)

⇒  W = (5*9800 N/m³)*(20 m*b*1 m) = (9.8*10⁵N/m)*b

Then, we apply

∑M₀ = 0  (counterclockwise)

- Fp*(h/3) + W*(b/2) = 0

⇒   - 1.96*10⁶N*(20 m/3) + (9.8*10⁵N/m)*b*(b/2) = 0

- 13.066*10⁶N-m + (4.9*10⁵N/m)*b² = 0

⇒  b = 5.164 m is the minimum thickness of the dam

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Given parameters:

Initial velocity of Coin = 0m/s

Time taken before coin hits ground  = 5.7s

Unknown:

Final velocity of the coin  = ?

Velocity is displacement with time. To solve this problem, we have to apply one of the equations of motion.

The fitting one of them here is shown below;

             V = U + gt

where;

V is the final velocity

U is the initial velocity

g is the acceleration due to gravity

t is the time taken

Here we use positive value of acceleration due to gravity because the coin is falling with the effect of acceleration and not against it.

Now input the parameters and solve;

               V  = 0 + 9.81 x 5.7

               V = 55.917m/s

Therefore, the final velocity is 55.917m/s.

8 0
3 years ago
Photovoltaic cells: a) have become more economical to produce and use over the past 25 years. b) are the most efficient means of
Yanka [14]

Photovoltaic cells are the most efficient means of converting solar energy to electricity. Option b is correct.

<h3>What is a cell?</h3>

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One or more cells can make up a battery. One cell, for example, is one AA battery.

Light intensity on a solar cell is often measured in "suns," with one sun roughly equivalent to 1 kW/m².

Concentrated sunlight improves the ratio of current generated while the device is lighted vs when it is dark, hence enhancing output voltage and efficiency.

Photovoltaic cells are the most efficient means of converting solar energy to electricity.

Hence, option b is correct.

To learn more about the cell refer to:

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8 0
2 years ago
1.)how is climate different from weather
Zolol [24]
(sorry I can only answer no. 1)
the climate is the weather over a long period of time (could be days, weeks, months, or years) while weather is only how the day has been on one day (e.g. sunny)
6 0
3 years ago
Suppose you "dig a hole" 52 feet deep and place a baseball machine in the hole, so that the balls fire out at 96 ft /s and land
jok3333 [9.3K]

Answer:

76.73 ft/s

Explanation:

Let the final velocity is v.

initial velocity, u = 96 ft/s

g = 32 ft/s²

height, h = 52 feet

use third equation of motion

v² = u² - 2 gh

v² = 96 x 96 - 2 x 32 x 52

v = 76.73 ft/s

Thus, the speed of the ball as it reaches the ground is 76.73 ft/s.

3 0
3 years ago
An LC circuit consists of a 3.400 capacitor and a coil with self-inductance 0.080 H and no appreciable resistance. At t = 0 the
Gnoma [55]

Answer:

Explanation:

charge on the capacitor = capacitance x potential

= 1.588 x 3.4

= 5.4 C  

Energy of capacitor  = 1 / 2 C V ² , C is capacitance , V is potential

=  .5 x 3.4 x 1.588²

= 4.29  J

If I be maximum current

energy of inductor = 1/2 L I² , L is inductance of inductor .

energy of inductance = Energy of capacitor

1/2 L I² = 4.29

I² = 107.25

I = 10.35 A

Time period of oscillation

T = 2π √ LC

=2π √ .08 X 3.4

= 3.275 s

current in the inductor will be maximum in T / 4 time

= 3.275 / 4

= .819 s.

Total energy of the system

= initial energy of the capacitor

=  4.29  J

7 0
3 years ago
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