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MAXImum [283]
3 years ago
8

Your backpack has a mass of 8 kg. You lift it from the ground to a height of

Physics
1 answer:
motikmotik3 years ago
3 0

Answer:

the answer will be 5.6 j..

hope you like the answer.....

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What would be your estimate of the age of the universe if you measured a value for Hubble's constant of H0 = 30 km/s/Mly ? You c
Maksim231197 [3]

Answer:

The age of the universe would be 9.9 billion years

Explanation:

We can calculate an estimate for the age of the Universe from Hubble's Law. Let's suppose the distance between two galaxies is D and the apparent velocity with which they are separating from each other is v. At some point, the galaxies were touching, and we can consider that time the moment of the Big Bang.

Thus, the time it has taken for the galaxies to reach their current separations is:

\displaystyle{t=D/v}

and from Hubble's Law:

v =H_0D

Therefore:

\displaystyle{t=D/v=D/(H_0\times D)=1/H_0}

With the given value for the Hubble's constant we have:

H_0=(30\ km/s/Mly) \times (1 Mly/ 9.461 \times 10^{18} km) = 3.17\times 10^{-18}\ 1/s

and thus,

t=1/H_0 = 1/(3.17\times 10^{-18} 1/s) = 0.315 \times 10^{18}\ s \approx 9988584474.8858\ years \approx 9.9\ billion\ years

6 0
3 years ago
The Drude model uses Newton’s laws, which say that an electron in a constant electric field should experience constant accelerat
Troyanec [42]

Answer:

Electrons are influenced by internal forces.

-On the temperature, density of electrons per unit of volume and relaxation time.

-The temperature

Explanation:

The Drude model neglects interactions between electrons and ions and with themselves. Those interactions (by which we refer as electromagnetic forces) influence in the random movement and freedom of the electron. So, they could be more restricted or could influence in conductivity more.

The deduction of the resistivity comes from the Ohm's law, which states that the Electric field in the material is proportional to the current density of electrons by a constant, which is the resistivity itself. The equation goes as follows:

\rho=\frac{m_e}{e^2n_e \tau }

Where e refers to electron (or the charge of it), τ is the relaxation time (average time between collisions), m is the mass and n is the density of charges (electrons in this case) per volume. However, experimentally resistivity is also dependent on temperature, which actually influence the relaxation time. The thermal energy influence in the behavior of the electrons, making them collide with phonons, have more randomness and reduced mean free path.

6 0
3 years ago
A baseball is hit almost straight up into the air with a speed of 26 m/s . Estimate how high it goes.
Natalka [10]

Answer:

The maximum height of the ball is 34.5 m.

The ball is 5.31 s in the air.

Explanation:

Hi there!

The equations for the height and velocity of the baseball that is hit straight up are as follows:

y = y0 + v0 · t + 1/2 · g · t²

v = v0 + g · t

Where:

y = height of the baseball at time t.

y0 = initial height.

v0 = initial velocity.

t = time.

g =  acceleration due to gravity (-9.8 m/s² considering the upward direction as positive).

v = velocity at time t.

If we place the origin of the frame of reference at the place where the baseball is hit, then, y0 = 0.

To calculate how high it goes, we have to obtain the time at which the ball is at maximum height. At that point, the velocity is 0. Then using the equation of velocity:

v = v0 + g · t

0 = 26 m/s - 9.8 m/s² · t

-26 m/s / -9.8 m/s² = t

t = 2.65 s

The height at that time will be the maximum height:

y = y0 + v0 · t + 1/2 · g · t²        (y0 = 0)

y = 26 m/s · 2.65 s - 1/2 · 9.8 m/s² · (2.65 s)²

y = 34.5 m

The maximum height of the ball is 34.5 m

If it takes the ball 2.65 s to reach the maximum height it will take another 2.65 s to return to the initial position. Then, the time it will be in the air is (2.65 s + 2.65 s) 5.30 s. However, let´s calculate the time it takes the ball to reach the initial position using the equation for height.

At the initial position y = 0. Then:

y = y0 + v0 · t + 1/2 · g · t²        (y0 = 0)

0 = 26 m/s · t - 1/2 · 9.8 m/s² · t²

0 = t (26 m/s - 1/2 · 9.8 m/s² · t)      (t = 0 when the ball is hit)

0 = 26 m/s - 1/2 · 9.8 m/s² · t

-26 / -4.9 m/s² = t

t = 5.31 s     ( the difference with the 5.30 s obtained above is due to rounding the time to 2.65 s).

The ball is 5.31 s in the air.

Have a nice day!

5 0
3 years ago
Why does psychics need a electrical current
nignag [31]

Answer:

Because Electrical Current is the most important thing about psychics

Explanation:

;p

3 0
3 years ago
Will brainlist 20 points
Len [333]

Your answer for this question is the third option.

3 0
2 years ago
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