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3 years ago

Which of the following is not a way that astronomers can find how much dark matter there is in cluster of galaxies?

Physics

1 answer:

Tpy6a [65]3 years ago

6 0

Answer:

b. Observe the radio waves coming from all dark matter; from the strength of the radio waves from each cluster, estimate the amount of dark matter needed to produce them.

Explanation:

The universe is thought to be made up of 85% dark matters. Dark matter is called dark because it does not appear to interact with the electromagnetic field, which means it doesn't absorb, reflect or emit electromagnetic radiation, and is therefore difficult to detect. This means that option b is wrong since radio wave is an electromagnetic wave. Dark matter is a form of matter that makes up about a quarter of the total mass–energy density of the universe. Dark matter was theorized due a variety of astrophysical observations and gravitational effects that cannot be explained by accepted theories of gravity unless there were more matter in the universe than can be seen.

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A 1.5 kilogram cart initially moves at 2.0 meters per second. It is brought to rest by a constant net forcé in 3.0 second. What

lubasha [3.4K]

The net force on the cart is

   Force = (mass) x (acceleration) .

We know the mass = 1.5 kilogram, but we need to
calculate the acceleration.

   Acceleration = (change in speed) / (time for the change)

Change in speed = (ending speed) minus (beginning speed)

   = ( 0 ) - ( 2 m/s ) =   -2 m/s

Acceleration = (change in speed) / (time for the change)

   = ( -2 m/s ) / (3 sec)

   = - 2/3 m/s² .

Finally ...    Net force = (mass) x (acceleration)

   = (1.5 kilogram) x ( - 2/3 m/s²)

   = ( - 3/2 x 2/3 ) (kg-m/s²)

   = - 1 newton .

The negative sign on the force means the force is applied
opposite to the direction the cart is moving. That gives
negative acceleration (slowing down), and the cart
eventually stops.

3 0

4 years ago

White light (light containing all frequencies of light in the visible spectrum) passes through a diffraction grating with 1300 l

lara31 [8.8K]

Answer:

The distance between the 1st order blue fringe and the 1st order red fringe is 6.5 cm.

Explanation:

Given that,

Diffraction grating =1300 lines/cm

Distance of screen = 2 m

Order number = 1

We need to calculate the distance between the 1st order blue fringe and the 1st order red fringe

Using formula of distance

For first order red fringe

$d\sin\theta=m\lambda$

$d\times\dfrac{y}{l}=m\times\lambda$

$y_{r}=\dfrac{m\times\lambda l}{d}$

$y_{r}=\dfrac{1\times700\times10^{-9}\times2}{\dfrac{1}{1300}\times10^{-2}}$

$y_{r}=0.182\ m$

For first order blue fringe

$y_{b}=\dfrac{1\times450\times10^{-9}\times2}{\dfrac{1}{1300}\times10^{-2}}$

$y_{b}=0.117\ m$

We need to calculate the distance between blue fringe and red fringe

$\Delta y=y_{r}-y_{b}$

$\Delta y=0.182-0.117$

$\Delta y=0.065\ m=6.5 cm$

Hence, The distance between the 1st order blue fringe and the 1st order red fringe is 6.5 cm.

7 0

3 years ago

Factfile about eclips

MAXImum [283]

Its quite hard to give you facts over this but just type into google facts about the sonar/lunar eclipse.

6 0

3 years ago

Hey! I need a response ASAP! Please answer all of the questions!

sesenic [268]

Answer: 7 is C,8 is B,9 is B,

Explanation: Give me a Like

3 0

2 years ago

A 975-kg pickup comes to rest from a speed of 87.5 km/h in a distance of 125 m. Suppose the pickup is initially traveling in the

Savatey [412]

Answer:

A) Force = 2303.925 N in the negative x-direction

B) F ≈ 143998.28 N

C) Ratio = 62.5

Explanation:

A) Since the brakes are the only thing making the van to come to a stop, then first of all, we will calculate the force (in a component along the direction of motion of the car) that the brakes will apply on the van.

Let's find the deceleration using Newton's law of motion formula;

v² = u² + 2as

where;

v = final velocity,

u = initial velocity,

s = displacement

a = acceleration

We are given;

u = 87.5 km/h = 24.3056 m/s

s = 125 m

v = 0 m/s

Thus;

0 = (24.3056)² + 2a(125)

- (24.3056)²= 250a

a = - 24.3056²/250

a = - 2.363 m/s²

Now, force = mass × acceleration

We are given mass = 975 kg

Thus;

Force = 975 x (-2.363)

Force = 2303.925 N in the negative x-direction

B) formula for kinetic energy is

KE = ½mv²

KE = ½(975)(24.3056)²

= 287996.568288 J

Work done on impact = F x 2

Thus;

2F = 287996.568288

F = 287996.568288/2

F ≈ 143998.28 N

C) Ratio = Force on car/braking force = 143998.284/2303.925 = 62.5

3 0

3 years ago