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3 years ago

What does the term Hubble time mean in cosmology, and what is the current best calculation for the Hubble time?

1 answer:

4 0

Hubble time in cosmology means the estimated age of the universe and the best calculation for it is T=1/H, where H is the Hubble constant

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I.Solve the following problems and answer the following questions. Show all your work and provide answers rounded off to the app

Ilia_Sergeevich [38]

The sprinter’s average acceleration is 1.98 m/s²

The given parameters;

initial velocity of the sprinter, u = 18 km/h

final velocity of the sprinter, v = 27 km/h

time of motion of the sprinter, t = 3.5 x 10⁻⁴ h

Convert the velocity of the sprinter to m/s;

$initial \ velocity, u = 18 \frac{km}{h} \times \frac{1000 \ m}{1 \ km} \times \frac{1 \ h}{3600 \ s} = 5 \ m/s\\\\final \ velocity, v =27 \frac{km}{h} \times \frac{1000 \ m}{1 \ km} \times \frac{1 \ h}{3600 \ s} = 7.5 \ m/s\\\\$

The time of motion is seconds;

$t = 3.5 \times 10^{-4} \ h \times \frac{3600 \ s}{1 \ h} = 1.26 \ s$

The sprinter’s average acceleration is calculated as follows;

$a = \frac{v- u}{t} \\\\a = \frac{7.5 \ m/s \ - \ 5 \ m/s}{1.26 \ s} \\\\a = 1.98 \ m/s^2$

Thus, the sprinter’s average acceleration is 1.98 m/s²

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6 0

3 years ago

What is one watt ? Write the relation of watt with kilowatt , megawatt , and horsepower .

alina1380 [7]

Answer:

See the explanation below

Explanation:

The watt (the power) is equal to the relationship between the work and the time in which that work is performed.

$P = W/t$

where:

W = work [J] (units of Joules)

t = time [s].

Now 1000 [W] are equal to 1 [kW]

And 1000000 [W] are equal to 1 [MW]

The horsepower is the unit of power in the imperial system of units.

And 745.7 [W] are equal to 1 [Hp]

3 0

3 years ago

Use the equation for magnetic force on a moving charge to derive the equation for magnetic force on a current carrying wire. Sho

max2010maxim [7]

Answer:

The formula comes from Lorentz force law which includes both the electric and magnetic field. If the electric field is zero, the force law for just the magnetic field is <u>F=q(ν×B</u>) . Here, F is force and is a vector because the force acts in a direction. q is the charge of the particle. v is velocity and is a vector because the particle is moving in some direction. B is the magnetic flux density.

We can derive an expression for the magnetic force on a current by taking a sum of the magnetic forces on individual charges. (The forces add because they are in the same direction.) The force on an individual charge moving at the drift velocity vd. Since the magnitude of B is constant at every line element of the loop (circle) and it dot product with the line element is B dl everywhere, therefore

∮B dl=μ0 I

B ∮dl=μ0 I

B 2πr=μ0 I

B=μ02πr Id=μ0/4π I dl×rr3

Since, r can be written as r=(rcosθ,rsinθ,z) and dl as dl=(dl,0,0) And now, if we take the cross product we would get

dl×r=−z dlj^+rsinθk^

and therefore the magnitude of dB is equal to

dB=μ0/4π I |dl×r|/r3=μ0/4π I z2+r2sin2θ−−−−−−−−−−√dl/r3

Thus, magnetic field is depending on r,θ,z.

Learn more about Force here-

brainly.com/question/2855467

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7 0

1 year ago

A person drives 4 miles east and the. 3 miles west

qwelly [4]

If a person drives 4 miles east, then 3 miles west, here are the facts:

They are 1 mile away from where they started.

They have driven a total of 7 miles.

7 0

3 years ago

The musical tone a piano has a frequency of 346HZ and a wavelength of 1.3 M what is the speed of the sound

prohojiy [21]

Answer:

v= 449.8 m/s

Explanation:

Given data

Frequency= 346Hz

Wave length= 1.4m

The expression below is used to find the speed

$v= f \lambda\\\\$

substitute

$v= 346*1.3\\\\v= 449.8 m/s$

Hence the speed is v= 449.8 m/s

5 0

3 years ago