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4 years ago

What is dark matter?

Physics

2 answers:

erastova [34]4 years ago

8 0

Dark matter is a hypothetical type of matter distinct from baryonic matter, neutrinos and dark energy.

Alinara [238K]4 years ago

5 0

Dark matter is a type of matter distinct from baryonic matter

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. A block of mass 4.0 kg on a spring has displacement as a function of time given by, x (t) = (1.0 cm) cos [(2.0 rad/s) t + 0.25

svlad2 [7]

Answer and Explanation:

1. Evaluate the function x(t) at t=0.5

$x(t)=1cos(2t+0.25)\\x(0.5)=cos(2*0.5+0.25)=cos(1+0.25)=cos(1.25)=0.3153223624\approx0.31cm$

2. The period of motion T can be calculated as:

$T=\frac{2\pi}{\omega}$

Where:

$\omega=2rad/s$

So:

$T=\frac{2\pi}{2}=\pi\approx3.14s$

3. The angular frequency can be expressed as:

$\omega=\sqrt{\frac{k}{m} }$

Solving for k:

$k=(\omega)^2*m=(2)^2*4=4*4=16\frac{N}{m}$

4. Find the derivate of x(t):

$\frac{dx}{dt} =v(t)=-2sin(2t+0.25)$

Now, the sine function reach its maximum value at π/2 so:

$2t+025=\frac{\pi}{2}$

Solving for t:

$t=\frac{\frac{\pi}{2} -0.25}{2} =0.6603981634s$

Evaluating v(t) for 0.6603981634:

$v(0.6603981634)=-2sin(2*0.6603981634+0.25)=-2sin(\frac{\pi}{2} )=-2*1=2$

So the maximum speed of the block is:

$v(0.6603981634)=2cm/s=0.02m/s$

In the negative direction of x-axis

5. The force is given by:

$F=kx$

The cosine function reach its maximum value at 2π so:

$2t+0.25=2\pi$

Solving for t:

$t=\frac{2\pi-0.25}{2} =3.016592654s$

Evaluating x(t) for 3.016592654:

$x(3.016592654)=cos(2*3.016592654+0.25)=cos(2\pi)=1cm=0.01m$

Therefore the the maximum force on the block is:

$F=16*0.01=0.16N$

6 0

3 years ago

Need help 8th grade work

Alisiya [41]

1) Ecology

2) Food Web

3) Trophic Level

4) Producer

5) Autotroph

6) Consumer

7) Heterotroph

8) Decomposer

Hope tHis Helps ._.

6 0

4 years ago

Read 2 more answers

Generators create (from nothing) electrical energy. true or false

Readme [11.4K]

False ! energy can not be created and for generators , they convert mechanical energy to electrical energy !

5 0

3 years ago

Read 2 more answers

Consider a 10 gram sample of a liquid with specific heat 2 J/gK. By the addition of 400 J, the liquid increases its temperature

stich3 [128]

40 J/g is the heat of vaporization of the liquid.

Answer: Option D

Explanation:

Given that mass of liquid sample: m = 10 g

And, Specific heat of the liquid: S = 2 J/g K

Also, the increase in the temperature of the liquid, $\Delta T = T_{2}-T_{1} = 10 K$

Therefore, the total amount of heat energy required is given by:

$q_{1} = m \times S \times\left(T_{2}-T_{1}\right) = 10 \times 2 \times 10 = 200 J$

According to the given data in the question,

Total heat energy supplied, q = 400 J

Rest of heat would be $q_{2}=q-q_{1}=400-200=200 \mathrm{J}$

Now, 200 J vaporizes the mass, half of the liquid from full portion boiled away. So,

$m^{\prime} = \frac{10}{2} = 5 \mathrm{g}$

Latent heat of vaporization of the liquid is $L_{v}$ . It can be calculated as below,

$q_{2} = m^{\prime} L_{v}$

$L_{v} = \frac{q_{2}}{m^{\prime}} = \frac{200}{5} = 40 \mathrm{J} / \mathrm{g}$

5 0

3 years ago

Felecia left her home to visit her daughter, driving 45mph. Her husband waited for the dog sitter to arrive and left home 20 min

andre [41]

Felicia** drove at 45 mph. After 1/3 of an hour, when her husband started out, she was (45/3) = 15 miles from home.

Husband drove at 55 mph. He gained (55-45) = 10 miles on Felicia each hour. That is, he closed 10 miles of the gap each hour.

It took him (15/10) = 1.5 hours to catch up to her.

That's 1hr 30min after HE started out, and 1hr 50min after SHE left the house.

** I've spelled the wife's name as 'Felicia' throughout my solution. I'm pretty sure there's a better chance of this being the correct spelling rather than 'Felecia', and I never trust anybody who can't spell their own name.

7 0

3 years ago

Read 2 more answers