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2 years ago

Why do scientists believe that dark matter exists even though it cannot be seen?

Physics

1 answer:

poizon [28]2 years ago

3 0

Because although they cannot see it, they can see it's influence on objects that can be seen, and it's effects.

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Does the number of particles change as the substance changes its state?

Leviafan [203]

Particles stay the same unless there is a chemical change whether the matter is solid, liquid or gas. ... When substances change state there is no change in mass so if 100 g of ice is melted 100g of water are formed this will boil to form 100g of steam (this is called "conservation of mass").

4 0

3 years ago

All known frequencies of the visible spectrum are..

crimeas [40]

Explanation:

$b. \: light$

7 0

2 years ago

A moonshiner makes the error of filling a glass jar to the brim and capping it tightly. The moonshine expands more than the glas

ohaa [14]

Answer:

ΔP = (640 N/cm^2)

Explanation:

Given:-

- The volume increase, ΔV/V0 = 4 ✕ 10^-3

- The Bulk Modulus, B = 1.6*10^9 N/m^2

Find:-

Calculate the force exerted by the moonshine per square centimeter

Solution:-

- The bulk modulus B of a material is dependent on change in pressure or Force per unit area and change in volume by the following relationship.

B = ΔP / [(ΔV/V)]

- Now rearrange the above relation and solve for ΔP or force per unit area.

ΔP = B* [(ΔV/V)]

- Plug in the values:

ΔP = (1.6*10^9)*(4 ✕ 10^-3)

ΔP = 6400000 N/m^2

- For unit conversion from N/m^2 to N/cm^2 we have:

ΔP = (6400000 N/m^2) cm^2 / (100)^2 m^2

ΔP = (640 N/cm^2)

7 0

3 years ago

Having landed on a newly discovered planet, an astronaut sets up a simple pendulum of length 1.38 m and finds that it makes 441

Tasya [4]

The period of a simple pendulum is given by:
$T=2 \pi \sqrt{ \frac{L}{g} }$
where L is the pendulum length, and g is the gravitational acceleration of the planet. Re-arranging the formula, we get:
$g= \frac{4 \pi^2}{T^2}L$ (1)

We already know the length of the pendulum, L=1.38 m, however we need to find its period of oscillation.

We know it makes N=441 oscillations in t=1090 s, therefore its frequency is
$f= \frac{N}{t}= \frac{441}{1090 s}=0.40 Hz$
And its period is the reciprocal of its frequency:
$T= \frac{1}{f}= \frac{1}{0.40 Hz}=2.47 s$

So now we can use eq.(1) to find the gravitational acceleration of the planet:
$g= \frac{4 \pi^2}{T^2}L = \frac{4 \pi^2}{(2.47 s)^2} (1.38 m) =8.92 m/s^2$

3 0

3 years ago

PLS HELP :) GIVING BRAINLIEST SIMPLE SCIENCE QUESTION HELPS PLSSSS

raketka [301]

OMG ITS B ITS B I HOPE I HELPED U

3 0

3 years ago