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natima [27]
3 years ago
5

The most important barriers to diffusion today are physical features of Earth's surface.

Physics
1 answer:
nikdorinn [45]3 years ago
7 0

Answer:

False

Explanation:

Physical features of earth's surface like mountains, deserts and oceans are not the barriers in today's modern world. Technological improvements in the transportation and communication has removed these barriers. So they are not barriers anymore.

You might be interested in
A CD player uses 1200 J of energy in 60 seconds what is the power rating of the CD player
tiny-mole [99]

The power equals energy divided by the time

P=E/t

P=1200/60

P=20W

Hope you get it!

8 0
3 years ago
The system consists of a 20-lb disk A, 4-lb slender rod BC, and a 1-lb smooth collar C. If the disk rolls without slipping, dete
dlinn [17]

Answer:

The velocity of the collar will be 3.076 ft/s

Explanation:

Given data

weight of the disk, Wa = 20lb

weight of rod BC, Wbc = 4lb

weight of collar, Wc = 1lb

Considering the equation of equilibrium

Vb = 1.5Wbc

Wa = 1.875 Wbc

to calculate the velocity of the collar using energy conservation equation

T1 + V1 = T2 + V2

0+4(1.5 \sin 45)+2(3 \sin 45)=\frac{1}{2}\left(\frac{1}{2}\left(\frac{20}{32.2}\right)(0.8)\right)              

=>(1.875 W b c)+\frac{1}{2}\left(\frac{20}{32.2}\right)(1.5 W b c)+\frac{1}{2}\left(\frac{20}{32.2}\right)

=>(1.5 W b c) \frac{1}{2}\left\{\frac{1}{12}\left(\frac{4}{32.2}\right)(3)\right\}+\frac{1}{2}\left(\frac{1}{32.2}\right)

=>(2.598 W b c)+4(1.5 \sin 0)+2(3 \sin 0)

Wbc = 1.18rad/sec

i.e.                                    

V _c=2.598 \times 1.18

= 3.076 ft/ s

5 0
3 years ago
A spherical balloon is deflating at 10 cm3/s. At what rate is the radius changing when the volume is 1000π cm3 ? What is the rat
just olya [345]

Answer:

1.dr/dt=0.0096cm/s

2. dA/dt=2.19cm^2/s

Explanation:

A spherical balloon is deflating at 10 cm3/s. At what rate is the radius changing when the volume is 1000π cm3 ? What is the rate of change of surface area at this moment?

for this question, we need to analyze the parameters we know

V=volume of the spherical balloon 1000π cm3

volume of the sphere=\frac{4}{3} \pi r^{3}

1000π=4/3πr^3

dividing both sides by 4

250*3=r^3

r=9.08cm, the radius of the balloon

dv/dt=dv/dr*dr/dt...................................1

dv/dr  ,means

V=\frac{4}{3} \pi r^{3}

dv/dr=4*pi*r^2

dv/dt=10 cm3/s

from equ 1

10=4*pi*9.08^2*dr/dt

10=1036 dr/dt

dr/dt=10/1036

dr/dt=0.0096cm/s

2. to find the rate at which the area is changing we have,

dA/dt=dA/dr*dr/dt

area of a sphere is  4πr^2

differentiate a with respect to r, radius

dA/dr=8πr

dA/dt=8πr*0.0096

dA/dt=8*pi*9.08*0.0096

dA/dt=2.19cm^2/s

is the rate of change of the surface area

7 0
3 years ago
Trong máy phát điện xoay chiều ba pha khi tổng điện áp tức thời của cuộn 1,2 là e1+e2=120V thì điện áp tức thời của cuộn 3 là
NARA [144]

Answer:

I just noticd i dont speak this launguage

Explanation:

8 0
3 years ago
A 10-kg projectile is fired straight up with an initial velocity of 500 m/s. (a) What is the projectile’s potential energy at th
Naily [24]
(a) the initial kinetic energy of the projectile is equal to:
K_i= \frac{1}{2}mv^2= \frac{1}{2}(10 kg)(500 m/s)^2=1.25 \cdot 10^6 J
The projectile is fired straight up, so at the top of its trajectory, its velocity is zero; this means that it has no kinetic energy left, so for the law of conservation of energy, all its energy has converted into potential energy, which is equal to
U_f=K_i= 1.25 \cdot 10^6 J

b) If the projectile is fired with an angle of 45^{\circ}, its velocity has 2 components, one in the x-direction and one in the y-direction:
v_x = v_0 \cos 45^{\circ} =(500 m/s) \cos 45^{\circ} =353.6 m/s
v_y = v_0 \sin 45^{\circ} = (500 m/s)(\sin 45^{\circ} )=353.6 m/s

This means that at the top of its trajectory, only the vertical velocity will be zero (because the horizontal velocity is constant, since the motion on the x-axis is a uniform motion). Therefore, at the top of the trajectory, the projectile will have some kinetic energy left:
K_f =  \frac{1}{2}m v_x^2 = \frac{1}{2} (10kg)(353.6 m/s)^2=6.25 \cdot 10^5 J
For the conservation of energy, the initial energy mechanical energy must be equal to the mechanical energy at the highest point:
K_i = K_f + U_f
the initial kinetic energy is the same as point a), so we can re-arrange this equation to find the new potential energy at the top of the trajectory:
U_f = K_i - K_f = 1.25 \cdot 10^6 J - 6.25 \cdot 10^5 J = 6.25 \cdot 10^5 J
7 0
3 years ago
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