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3 years ago

15

How many molecules are indicated by writing 2 H2O? A.) 2 B.) 3 C.) 4 D.) 1

2 answers:

Thepotemich [5.8K]3 years ago

7 0

A, 2 molcules
H2O is one molecule, it has 3 atoms (two hydrogen and one oxygen)
2 H2O are two water molecules

Svet_ta [14]3 years ago

4 0

There are three total molecules in H2O, but the two represents the number of Hyrdogen molecules. So the 2 represents 2 molecules

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A light platform is suspended from the ceiling by a spring. A student with a mass of 90 kg climbs onto the platform. When it sto

Ilya [14]

Refer to the diagram shown.

When the student climbs onto the platform, the spring stretches by 0.82 m to reach the equilibrium position.
The mass of the student is m = 90 kg, so his weight is
mg = (90 kg)*(9.8 m/s²) = 882 N

By definition, the spring constant is
k = (882 N)/(0.82 m) = 1075.6 N/m

When the spring is stretched by x from the equilibrium position, the restoring force is
F = - k*x.

If damping is ignored, the equation of motion is
F = m * acceleration
or
$m \frac{d^{2}x}{dt^{2}} = -kx \\ \frac{d^{2}x}{dt^{2}} + \frac{k}{m} x = 0$

Define ω² = k/m = 11.751 => ω = 3.457.
Then the solution of the ODE is
x(t) = c₁ cos(ωt) + c₂ sin(ωt)

x'(t) = -c₁ω sin(ωwt) + c₂ω cos(ωt)
When t=0, x' =0, therefore c₂ = 0

The solution is of the form
x(t) = c₁ cos(ωt)
When t = 0, x = 0.32 m. Therefore c₁ = 0.32

The motion is
x(t) = 0.32 cos(3.457t)
The single amplitude is 0.32 m, and the double amplitude is 0.64 m.

Answer:
0.32 m (single amplitude), or
0.64 m (double amplitude)

6 0

3 years ago

The magnitude of an electron's charge is e=1.60\times 10^{-19}\,\text{C}e=1.60×10 −19 Ce, equals, 1, point, 60, times, 10, start

Tresset [83]

Answer:

Explanation:

Conclusion is simple you can just say that it is the value written in words form only.

Nothing else is written about it

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3 years ago

A measure of how easily current will pass through a material ?

Jlenok [28]

Answer:

It is Conductivity because it is the measure of the ease.

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3 years ago

Radar is used to determine distances to various objects by measuring the round-trip time for an echo from the object. (a) How fa

zloy xaker [14]

Answer:

150000000000 m

0.0000005 seconds

33.33 ns

Explanation:

Speed of electromagnetic waves through vacuum = $3\times 10^8\ m/s$

Echo time = 1000 seconds

Echo time is the time taken to reach the object and come back to the observer

Distance = Speed×Time

$Distance=3\times 10^8\times \frac{1000}{2}=150000000000\ m$

Venus is 150000000000 m away from Earth

Time = Distance / Speed

$Time=\frac{75}{3\times 10^8}=0.00000025\ seconds$

Echo time will be twice the time

$Echo\ time=2\times 0.00000025=0.0000005\ seconds$

The echo time will be 0.0000005 seconds

Difference in time = Difference in distance / Speed

$\Delta t=\frac{\Delta d}{v}\\\Rightarrow \Delta t=\frac{10}{3\times 10^8}\\\Rightarrow \Delta=33.33\ ns$

The accuracy by which I will be able to measure the echo time is 33.33 ns

5 0

4 years ago

The angular speed of digital video discs (DVDs) varies with whether the inner or outer part of the disc is being read. (CDs func

Kitty [74]

Answer:

α = 0.0135 rad/s²

Explanation:

given,

t = 133 min = 133 x 60 = 7980 s

angular speed varies from 570 rpm to 1600 rpm

now,

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= 59.69 rad/s

1600 rpm = = $570 \times \dfrac{2\pi}{60}$

= 167.6 rad/s

using equation of rotational motion

ωf = ωi + αt

167.6 = 59.7 + α x 7980

α x 7980 = 107.9

α = 0.0135 rad/s²

8 0

3 years ago