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4 years ago

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1pt Which is an observation? O A. A person hears the song of a bird. OB. A person suggests that bird calls are a means of commun

ication. O C. A person concludes that bird calls attract mates. OD. A person writes a paper describing different kinds of bird calls....

1 answer:

Doss [256]4 years ago

3 0

Answer:

D

Explanation:

he describes as he writes them down

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Compare the densities of two objects that have the same volume, but one feels heavier than the other.

motikmotik

We know, density = Mass / Volume
It represents density is directly proportional to mass and indirectly proportional to volume. So, at a constant volume, object with larger density will appear more heavier than that of object with smaller density.

In short, Heavier object will have the higher density than the other.

Hope this helps!

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3 years ago

Water, in a 100-mm-diameter jet with speed of 30 m/s to the right, is deflected by a cone that moves to the left at 14 m/s. Dete

podryga [215]

Answer:

Explanation:

The velocity at the inlet and exit of the control volume are same $V_i=V_e=V$

Calculate the inlet and exit velocity of water jet

$V=V_j+V_e\\\\V=30+14\\\\V=44m/s$

The conservation of mass equation of steady flow

$\sum ^e_i\bar V. \bar A=0\\\\(-V_iA_i+V_eA_e)=0$

$A_i\ \texttt {is the inlet area of the jet}$

$A_e\ \texttt {is the exit area of the jet}$

since inlet and exit velocity of water jet are equal so the inlet and exit cross section area of the jet is equal

The expression for thickness of the jet

$A_i=A_e\\\\\frac{\pi}{4} D_j^2=2\pi Rt\\\\t=\frac{D^2_j}{8R}$

R is the radius

t is the thickness of the jet

D_j is the diameter of the inlet jet

$t=\frac{(100\times10^{-3})^2}{8(230\times10^{-3}} \\\\=5.434mm$

(b)

$R-x=\rho(AV_r)[-(V_i)+(V_c)\cos 60^o]\\\\=\rho(V_j+V_c)A[-(V_i+V_c)+(V_i+V_c)\cos 60^o]\\\\=\rho(V_j+V_c)(\frac{\pi}{4}D_j^2 )[V_i+V_c](\cos60^o-1)]$

$1000kg/m^3=\rho\\\\44m/s=(V_j+V+c)\\\\100\times10^{-3}m=D_j$

$R_x=[1000\times(44)\frac{\pi}{4} (10\times10^{-3})^2[(44)(\cos60^o-1)]]\\\\=-7603N$

The negative sign indicate that the direction of the force will be in opposite direction of our assumption

Therefore, the horizontal force is -7603N

7 0

3 years ago

What do scientist use to look at astronomical bodies?

ivann1987 [24]

The answer should be C. :)

6 0

4 years ago

Read 2 more answers

You replace a 100 W incandescent lightbulb with a 22 W CFL bulb. If you leave your lights on 24 hours a day, how much energy are

crimeas [40]

100 watts = 100 joules per second
22 watts = 22 joules per second
Saving = 78 joules per second

1 hour = 3,600 seconds
24 hours = 86,400 seconds

(78 joules/sec) x (86,400 sec) = 6,739,200 joules

5 0

3 years ago

A2 kg block is accelerating at the rate of 5 m/s² while being acted on by two forces. One of the forces equals 30 N, 0°. What ar

Mademuasel [1]

Answer:

20 [N], in the opposite direction of the first force.

Explanation:

We know that newton's second law stipulates that the sum of forces on a body must be equal to the product of mass by acceleration.

$SumF = m*a\\30 + F = 2*5\\F = 30 - (2*5)\\F = - 20 [N]$

The negative sign means that the other force acting on the body must be in the opposite direction to the force of 30 [N]

6 0

3 years ago