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3 years ago

A rock is dropped into the Grand Canyon. It takes 18 seconds to hit the bottom. Calculate how deep the canyon is.

1 answer:

6 0

The distance it falls is given by
x = (1/2)at^2
where a = acceleration due to gravity = 9.8 m/s^2
x = (1/2)(9.8)(18)^2
x = 1587.6 m
The answer is 1587.6 meters

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What is the speed of a commercial jet which travels form New York to Los Angeles (4800) in 6 hours

Colt1911 [192]

Answer:

$Speed = 800km}/hr$

Explanation:

Given

$Distance = 4800km$

$Time = 6hr$

Required

Determine the speed of the jet

The speed is calculated as:

$Speed = \frac{Distance}{Time}$

Substitute 4800 km for Distance and 6hr for Time

$Speed = \frac{4800km}{6hr}$

$Speed = 800km}/hr$

<em>Hence, the speed of the commercial jet is 800km/hr</em>

8 0

3 years ago

Concrete colums are constructed with reinforcing steel in them to make them stronger and more ductile. The reinforcing bars are

Sergio039 [100]

Answer:

$21678.47223\ lbf-in^2$

$383.1109\ lbf-in^2$

Explanation:

d = Diameter of column = 0.5 inch

$A_c$ = Area of concrete = $119.4\ in^2$

The strain in the system is conserved

$\dfrac{F_sL}{A_sE_s}=\dfrac{F_cL}{A_cE_c}\\\Rightarrow F_c=\dfrac{F_sA_cE_c}{A_sE_s}\\\Rightarrow F_c=\dfrac{F_s \times 119.4\times 4.1\times 10^6}{8\times \dfrac{\pi \dfrac{1}{2^2}}{4}\times 29\times 10^6}\\\Rightarrow F_c=10.74658F_s$

Now

$F_c+F_s=50000\\\Rightarrow 10.74658F_s+F_s=50000\\\Rightarrow F_s=\dfrac{50000}{11.74658}\\\Rightarrow F_s=4256.55807\ lbf$

$F_c=10.74658F_s\\\Rightarrow F_c=10.74658\times 4256.55807\\\Rightarrow F_c=45743.44182\ lbf$

Stress is given by

$\sigma_s=\dfrac{4256.55807}{\pi \dfrac{1}{2^2}}{4}\\\Rightarrow \sigma_s=21678.47223\ lbf-in^2$

The stress in the steel is $21678.47223\ lbf-in^2$

$\sigma_c=\dfrac{45743.44182}{119.4}\\\Rightarrow \sigma_s=383.1109\ lbf-in^2$

The stress in the steel is $383.1109\ lbf-in^2$

4 0

3 years ago

Which of the following describes the importance of cyanobacteria to early Earth atmosphere formation?

Dmitrij [34]

I do believe it is a

6 0

3 years ago

Which of the following changes would cause the fusion rate in the Sun’s core to increase? Check all that apply. View Available H

fredd [130]

Answer:

1. An increase in the core temperature

2. A decrease in the core radius.

Explanation:

The sun is a Main Sequence star. A Main Sequence star is powered by fusing hydrogen into Helium within its core.

For this fusion to take place, a temperature of at least 10 million Kelvin is required, beyond this point, the fusion rate is directly related to the core temperature. If the temperature increases, the fusion rate will greatly increase.

Something similar happens if the core reduces its radius. This can happen at the end of the star's lifetime, shortly before it becomes a red giant. Once the hydrogen is depleted, the core will start to shrink because the force of gravity, and as it gets smaller, gets more compressed, and its temperature increases. The outer layers of remaining Hydrogen that were outside the core now begin to heat up, and as the core continues to shrink, the star gets hot enough to begin the fusion process again, and the fusion rate can even be higher than it was during the first phase of the star, as the star becomes a Red Giant.

7 0

3 years ago

What percentage of the nations demand for electricity could be produce in the future by wind energy?

Furkat [3]

In the future ? Well, there's no technological reason why it couldn't be 100%.

8 0

3 years ago