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3 years ago

The big bang theory has finally answered one of the biggest questions of science—the origin of the universe.

Physics

1 answer:

ss7ja [257]3 years ago

6 0

Answer:

False

Explanation:

According to the big bang theory, matter was an infinitely small and very high density point which at one point exploded and expanded in all directions, creating what we know as our Universe, which also includes space and time . This happened about 13.8 billion years ago. Theoretical physicists have managed to reconstruct this chronology of events from 1/100 of a second after the Big Bang. After the explosion, while the Universe expanded, it cooled sufficiently and the first subatomic particles were formed: Electrons, Positrons, Mesons, Barions, Neutrinos, Photons among others. Today more than 90 particles are known. This theory solves many unknowns and is very well received by the scientific community, however there is still much to solve, for example, one of the great unsolved scientific problems in the expanding Universe model is whether the Universe is open or closed.

An attempt to solve this problem is to determine if the average density of matter in the Universe is greater than the critical value in Friedmann's model. The mass of a galaxy can be measured by observing the movement of its stars; multiplying the mass of each galaxy by the number of galaxies, it is seen that the density is only 5 to 10% of the critical value.

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Plz help me

Reil [10]

Answer:

Yes

Explanation:

When an object has more mass it takes more gravity to keep it down therefore producing friction which in return reduces the amount of kinetic energy created. A change in an object's speed has an greater effect on its kinetic energy. than a change in its mass has, because kinetic energy is proportional to.

3 0

4 years ago

On a safety test course, a 1000 kg car heading north at 5 m/s collides head-on with an 800 kg car heading south at 4 m/s. At the

Luden [163]

Answer:

The speed is $3.5\frac{m}{s}$ and the direction is heading north.

Explanation:

In collisions the force exerted by the objects that collide is higher enough than the external forces that we can neglect that external forces, with that assumption we can use the conservation fo momentum law that states, final total momentum (pf) is equal initial total momentum (pi) if there’re not external forces or they are small enough to be neglected. Mathematically:

$p_f=p_i$

The total momentum is the sum of the momentum of each of the bodies we're dealing, in our case the moment of each car, then:

$p_{nf}+p_{sf}=p_{ni}+p_{si}$

with pn the momentum of the 1000kg car heading north and ps the 800kg car heading south. Momentum is defined as mass times velocity, then:

$m_nv_{nf}+m_sv_{sf}=m_nv_{ni}+m_sv_{si}$ (1)

It's important to note that when we talk about momentum and velocity direction matters, so we're are going to choose a system of reference where quantities pointing north are positive and pointing south are negative. So, the initial velocity of 1000 kg car is vni=5 m/s, initial velocity of 800 kg car is vsi=-4 m/s and the final velocity of 1000 kg car is vnf=-1 m/s. Now we can solve (1) for vsf and use the values we already have:

$v_{sf}=\frac{m_nv_{ni}+m_sv_{si}-m_nv_{nf}}{m_s}=\frac{(1000)(5)+(800)(-4)-(1000)(-1)}{800}$

$v_{sf}=3.5\frac{m}{s}$

Because the sign is positive the direction is to heading north.

7 0

3 years ago

An Airbus A380 airliner can takeoff when its speed reaches 80 m/s. Suppose its engines together can produce an acceleration of 3

Tomtit [17]

Answer:

(a). The time is 26.67 sec.

(b). The distance traveled during this period is 1066.9 m.

Explanation:

Given that,

Speed = 80 m/s

Acceleration = 3 m/s

Initial velocity = 0

(a). We need to calculate the time

Using equation of motion

$v = u+at$

$t = \dfrac{v-u}{a}$

Put the value into the formula

$t = \dfrac{80-0}{3}$

$t =26.67\ sec$

The time is 26.67 sec.

(b). We need to calculate the distance traveled during this period

Using equation of motion

$s = ut+\dfrac{1}{2}at^2$

$s = 0+\dfrac{1}{2}\times3\times(26.67)^2$

$s =1066.9\ m$

The distance traveled during this period is 1066.9 m.

Hence, This is the required solution.

7 0

3 years ago

A thin layer of oil of refractive index 1.22 is spread on the surface of water (n = 1.33), If the thickness of the oil is 275 nm

ANTONII [103]

Answer:

6.71×10⁻⁷ m

Explanation:

Using thin film constructive interference formula as:

Where,

n is the refractive index of the refracted surface

t is the thickness of the surface

λ is the wavelength

If m =1

Then,

2×n×t = λ

Given that refractive index pf the oil is 1.22

Thickness of the oil = 275 nm

Also, 1 nm = 10⁻⁹ m

Thickness = 275×10⁻⁹ m

So,

Wavelength is :

8 0

4 years ago

Answer the following questions for projectile motion on level ground assuming negligible air resistance (the initial angle being

NikAS [45]

Answer:

Explanation:

a ) The velocity will never be zero . The velocity will be minimum at the highest point of projectile, which will be equal to the horizontal component of the initial velocity.

b ) The velocity will be minimum when its kinetic energy will be minimum . Kinetic energy will be minimum when its potential energy will be maximum.

Its potential energy will be maximum at the highest point so velocity will be minimum at the highest point.

c ) Velocity will never be the same as initial velocity because constant force of gravitation is acting on the projectile all the time.

d ) At the moment when the projectile returns back and hits the ground, the speed becomes equal to the initial speed ( at t = 0 ) because its kinetic energy becomes the same as initial energy , the height becoming zero.

6 0

4 years ago