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4 years ago

Which of the following is true of salt lakes?

Physics

2 answers:

Thepotemich [5.8K]4 years ago

8 0

<span>A) The water flowing in to salt lakes comes directly from the ocean.

Hope this helps!</span>

bonufazy [111]4 years ago

3 0

Answer: b. Salt lakes are formed when river bends are cut off.

Salt lakes are formed when water from water sourced gets accumulated in a shallow region and the supply of water is cut. These salt lakes are terminal which means water does not flow to other locations. Therefore, salt lakes are formed when river bends are cut off.

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Your friend says the following to you: "The lungs are the main

posledela

The respiratory system is made up of multiple organs, saying that the lungs is the only required organ is very wrong. While the lungs are probably the most important part of it, the organs that transfer the air are definitely necessary for everything to work.

The main organ that is needed for air to flow from the mouth to the lungs is the trachea, or the windpipe. This connects the back of the mouth to the lungs, without this, no air could get into the lungs, thus rendering them useless.

7 0

3 years ago

These waves are most harmful for living things.

scZoUnD [109]

Explanation:

G. gamma rays because they are produced by the hottest and most energetic objects in the universe, such as neutron stars and pulsars, supernova explosions, and regions around black holes.

hope this helps you

have a nice day:)

5 0

3 years ago

A tennis ball is dropped from a height of 10.0 m. It rebounds off the floor and comes up to a height of only 4.00 m on its first

Dominik [7]

Answer:

a) $V=14.01 m/s$

b) $V=8.86 \, m/s$

c) $t = 2.33s$

Explanation:

Our most valuable tool in solving this problem will be the conservation of mechanical energy:

$E_m = E_k +E_p$

That is, mechanical energy is equal to the sum of potential and kinetic energy, and the value of this $E_m$ mechanical energy will remain constant. (as long as there is no dissipation)

For a point particle, we have that kinetic energy is:

$E_k = \frac{1}{2} m \, V^2$

Where m is the mass, and V is the particle's velocity,

Potential energy on the other hand is:

$E_p= m\, g\, h$

where g is the acceleration due to gravity ( $g=9.81 \, m/s^2$ ) and h is the height of the particle. How do we define the height? It's a bit of an arbitrary definition, but we just need to define a point for which $h=0$ , a "floor". conveniently we pick the actual floor as our reference height, but it could be any point whatsoever.

Let's calculate the mechanical energy just before the ball is dropped:

As we drop the ball, speed must be initially zero, and the height from which we drop it is 10 meters, therefore:

$E_m = \frac{1}{2}m\,0^2+ mg\cdot 10 \,m\\E_m=mg\cdot10 \, m$

That's it, the actual value of m is not important now, as we will see.

Now, what's the potential energy at the bottom? Let's see:

At the bottom, just before we hit the floor, the ball is no longer static, it has a velocity V that we want to calculate, on the other hand, it's height is zero! therefore we set $h=0$

$E_m = \frac{1}{2}m\,V^2+ mg\cdot 0\\\\E_m = \frac{1}{2}m\,V^2$

So, at the bottom, all the energy is kinetic, while at the top all the energy is potential, but these energies are the same! Because of conservation of mechanical energy. Thus we can set one equal to the other:

$E_m = \frac{1}{2}m\,V^2 = mg\cdot 10m\\\\\\ \frac{1}{2}m\,V^2 = mg\cdot 10m\\\\V = \sqrt[]{2g\cdot 10m} \\$

And so we have found the velocity of the ball as it hits the floor.

$V = \sqrt[]{2g\cdot 10m}=14.01\, m/s$

Now, after the ball has bounced, we can again do an energy analysis, and we will get the same result, namely:

$V = \sqrt[]{2g\cdot h}$

where h is the maximum height of the ball, and v is the maximum speed of the ball (which is always attained at the bottom). If we know that now the height the ball achieves is 4 meters, plugging that in:

$V = \sqrt[]{2g\cdot 4m} =8.86 \, m/s$

Now for C, we need to know for how long the ball will be in the air from the time we drop it from 10 meters, and how long it will take the ball to reach its new maximum height of 4 meters.

As the acceleration of gravity is a constant, that means that the velocity of the ball will change at a constant rate. When something changes at a constant rate, what is its average? It's the average between initial and final velocity, look at diagram to understand. The area under the Velocity vs time curve is the displacement of the ball, and:

$V_{avg}\cdot t=h\\t=h/V_{avg}$

what's the average speed when the ball is descending?

$V_{avg}=\frac{1}{2} (14.01\, m/s+0)=7 \, m/s$

so the time it takes the ball to go down is:

$t=h/V_{avg}=\frac{10m}{7m/s} =1.43s\\$

Now, when it goes up, it's final and initial speeds are 0 and 8.86 meters per second, thus the average speed is:

$V_{avg}=\frac{1}{2} (8.86\, m/s+0)=4.43 \, m/s$

and the time it takes to go up is: $t=h/V_{avg}=\frac{4m}{4.43m/s} =0.90s$

When we add both times , we get:

$t_{total}=t_{down}+t_{up}=1.43s+0.90s = 2.33s$

6 0

3 years ago

A timline is necessary :

kolezko [41]

Answer:

A. For every goal

Explanation:

A timeline is necessary for every goal set, be it academic, life, high school, personal, and the like. A timeline is an important part of goal setting. It helps determine what should be done by a certain time to ensure that you will reach your goal. Although some goals can take a long time to reach, a timeline will be your constant reminder of what needs to be done.

When setting a timeline, you also need to take in consideration what you want to achieve. You need to set a realistic timeline as many usually underestimate the obstacles they may face in pursuing their goals.

8 0

4 years ago

A 12 g plastic ball is dropped from a height of 2.5 m and is moving at 3.2 m/s just before it hits the floor. How much mechanica

Nataly [62]

Answer:

0.24

Explanation:

Mass of ball= 12g=0.012Kg

height of ball= 2.5m

velocity of ball before falling= 3.2m/s

potential energy of the ball=mgh= 0.012*10*2.5=0.3J

kinetic energy of the ball=0.5*m $v^{2}$ =0.5*0.012*3.2*3.2=0.6J

Loss in mechanical energy during the fall= potential energy- Kinetic energy= 0.3-0.06=0.24J

note: During the fall, the potential energy of the ball is converted to kinetic energy. the loss in energy is due to air resistance.

4 0

3 years ago