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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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An emf of 28.0 mV is induced in a 501 turn coil when the current is changing at a rate of 12.0 A/s. What is the magnetic flux th

dmitriy555 [2]

Answer:

Φ = 5.589×10⁻⁵ Wb

Explanation:

The inductance of a coil is given as

L = e/(di/dt) ..................... Equation 1

Where L = inductance of the coil, e = induced e.m.f, di/dt = rate of change of current in the coil.

Also,

The inductance of each turn of the coil when a magnetic field is step up in the coil is

L = NΦ/i ................. Equation 2

Where N = number of turns, Φ = magnetic field, i = current.

equating equation 1 and equation 2

e/(di/dt) = NΦ/i

making Φ the subject of the equation,

Φ = (e×i)/N.(di/dt) .................. Equation 3

Given: e = 28.0 mV = 0.028 V, N = 501 turns, di/dt = 12.0 A/s, i = 4.00 a

Substitute into equation 3,

Φ = (0.028×4)/(12×501)

Φ = 0.112/2004

Φ = 5.589×10⁻⁵ Weber

Φ = 5.589×10⁻⁵ Wb

6 0

3 years ago

What shape is the graph produced by a force vs acceleration graph?

hammer [34]

The answer to the question<u> What shape is the graph produced by a force vs acceleration graph</u> is A. Linear

Since Force, F = ma where m = mass and a = acceleration. For constant mass, F ∝ a. That is, F is directly proportional to acceleration, a.

Since this is a linear relationship, the graph of force vs acceleration will be linear.

The answer to the question<u> What shape is the graph produced by a force vs acceleration graph</u> is A. Linear

Learn more about graphs here:

brainly.com/question/24322515

6 0

2 years ago

A subway train starts from rest at a station and accelerates at a rate of 1.68 m/s2 for 14.2 s. It runs at constant speed for 68

liubo4ka [24]

Answer:

total distance = 1868.478 m

Explanation:

given data

accelerate = 1.68 m/s²

time = 14.2 s

constant time = 68 s

speed = 3.70 m/s²

to find out

total distance

solution

we know train start at rest so final velocity will be after 14 .2 s is

velocity final = acceleration × time ..............1

final velocity = 1.68 × 14.2

final velocity = 23.856 m/s²

and for stop train we need time that is

final velocity = u + at

23.856 = 0 + 3.70(t)

t = 6.44 s

and

distance = ut + 1/2 × at² ...........2

here u is initial velocity and t is time for 14.2 sec

distance 1 = 0 + 1/2 × 1.68 (14.2)²

distance 1 = 169.37 m

and

distance for 68 sec

distance 2= final velocity × time

distance 2= 23.856 × 68

distance 2 = 1622.208 m

and

distance for 6.44 sec

distance 3 = ut + 1/2 × at²

distance 3 = 23.856(6.44) - 0.5 (3.70) (6.44)²

distance 3 = 76.90 m

total distance = distance 1 + distance 2 + distance 3

total distance = 169.37 + 1622.208 + 76.90

total distance = 1868.478 m

7 0

3 years ago

Read 2 more answers

a man is standing near the edge of a cliff 85 meters high. he throws a stone upward vertically with an intial velocity of 10 m/s

alex41 [277]

Answer:

h = 90.10 m

Explanation:

Given that,

A man is standing near the edge of a cliff 85 meters high, h₀ = 85 m

The initial speed of the stone, u = 10 m/s

The path followed by the projectile is given by :

$h(t)=-4.9t^2+10t+85$ ....(1)

For maximum height,

Put dh/dt = 0

So,

$\dfrac{dh}{dt}=-9.8t+10=0\\\\t=\dfrac{10}{9.8}\\\\=1.02\ s$

Put the value of t in equation (1).

$h(t)=-4.9(1.02)^2+10(1.02)+85\\\\=90.10\ m$

So, the maximum height of the stone is equal to 90.10 m.

5 0

3 years ago

Does a good insulator prevent energy from getting through it, or slow its passage

9966 [12]

A good heat insulator absorbs all, or almost all, of the heat energy
from any heat that flows through it.

A good electrical insulator absorbs all, or almost all, of the energy
from any electric current that flows through it.

8 0

3 years ago