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Romashka [77]
3 years ago
7

Why is it hard to breathe when you go higher up

Physics
1 answer:
Fantom [35]3 years ago
8 0

When we breathe in air at sea level, the atmospheric pressure of about 14.7 pounds per square inch (1.04 kg. per cm.2) causes oxygen to easily pass through selectively permeable lung membranes into the blood. At high altitudes, the lower air pressure makes it more difficult for oxygen to enter our vascular systems.

hope this helps :)

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A factory worker pushes a 30.0-kg crate a distance of 4.5 m along a level floor at constant velocity by pushing horizontally on
SIZIF [17.4K]

(a) 73.5 N

The velocity of the crate is constant: this means that the acceleration is zero (a=0), so according to Newton's second law

\sum F = ma

the resultant of the forces must be zero: \sum F = 0 (1)

The motion is along the horizontal direction, so we are only interested in the forces acting along this direction. There are two of them:

F, the push applied by the worker

F_f=-\mu mg, the force of friction, with \mu=0.25 being the coefficient of friction, m=30.0 kg being the mass of the crate, and g=9.8 m/s^2. The negative sign is due to the fact that the friction acts in the opposite direction to the motion. Eq.(1) then becomes

F-\mu mg=0\\F=\mu mg=(0.25)(30.0 kg)(9.8 m/s^2)=73.5 N

So, this is the force that the worker must apply.

(b) 330.8 J

The work done by the pushing force of the worker on the crate is given by:

W=Fd cos \theta

where

F = 73.5 N is the force

d = 4.5 m is the displacement

\theta=0^{\circ} is the angle between the direction of the force and the displacement (0 degrees, since they are in same direction)

Substituting, we have

W=(73.5 N)(4.5 m)(cos 0^{\circ})=330.8 J

(c) -330.8 J

To calculate the work done by friction, we apply the same formula:

W=F_f d cos \theta

where

F_f = \mu mg=(0.25)(30.0 kg)(9.8 m/s^2)=73.5 N is the magnitude of the force of friction

d = 4.5 m is the displacement

\theta=180^{\circ} is the angle between the direction of the force of friction and the displacement (it is 180 degrees since the two are into opposite directions)

Substituting, we find

W=(73.5 N)(4.5 m)(cos 180^{\circ})=-330.8 J

So, the work done by friction is negative.

(d) 0 J

As before, the work done by any force on the crate is

W=F_f d cos \theta

We notice that both gravity and normal force are perpendicular to the displacement: therefore, \theta=90^{circ}, and so

cos \theta=0

which means that the work done by both forces is zero.

(e) 0 J

The total work done on the crate is the sum of the work done by the four forces acting on it, so:

W=W_{push} + W_{friction}+W_{gravity}+W_{normal}=330.8J-330.8J+0+0=0

And this is in accordance with the work-energy theorem, which states that the variation of kinetic energy of the crate is equal to the work done on it: since the crate is moving at constant velocity, its variation of kinetic energy is zero, as well as the work done on it.

5 0
2 years ago
Imagine you are holding an apple. how could you increase the potential energy of this apple?
Ray Of Light [21]

If you're holding the apple at your waist, lift it to your mouth.
Potential energy relative to any level is proportional to its height
above that level.  Increase that height, and you've increased the
potential energy.

Since energy is conserved ... it never magically appears or
disappears ... you need to tell where that extra energy for the
apple came from.

It's exactly the work you did ... the force of your muscles acting
through the distance you raised the apple ... that became the
additional potential energy that the apple gained.

6 0
2 years ago
What kind of scattering (Rayleigh, Mie, or non-selective) would you expect to be most important when radiation of the specified
oee [108]

Answer:

hello your question is not properly arranged attached below is the arranged table and solution

answer : attached table below

Explanation:

Given data:

02 molecules size = 10^-10m

smoke particles size = 0.3 mm

cloud droplets size = 20 mm

Rain droplets size = 3 mm

Attached below is a table showing the kind of scattering that is expected to occur at various wave lengths

Note : For Rayleigh scattering the wave particle is smaller than the wave length while for Non-selective scattering the wave particle is greater than the wavelength.

and  For Mie scattering the wavelength is the same as the wavelength.

3 0
2 years ago
A 0.5 kg turntable with a radius of 15 cm is rotating 78 times per minute.
alexandr1967 [171]

Answer:

c

Explanation:

8 0
2 years ago
Choose the word that best completes each sentence.
vladimir2022 [97]
Plants are autotrophs

Animals are heterotrophs
7 0
2 years ago
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