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4 years ago

Dark matter may explain _____.

Physics

2 answers:

tia_tia [17]4 years ago

5 0

Answer: A.unexpected orbital velocities of stars in galaxies

Explanation:

Dark Matter makes up about 80% of matter in the universe. This matter does not emit light and hence, it is called dark matter as it cannot be observed directly.

The effect of the presence of the dark matter is unexpected orbital velocities of stars in galaxies. At the center, the orbital velocities are greater than those at the edge. Had there been no dark matter, the galaxy would have flown apart.

Lisa [10]4 years ago

4 0

Dark matter may explain <span>unexpected orbital velocities of stars in galaxies.</span>

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a 1.5 kg ball is thrown vertically upward with an initial speed of 15 m/s. if the initial potential energy is taken as zero, fin

trapecia [35]

Answer:

a) $E_{p} = 0$

$E_{k} = 168.7 J$

$E_{m} = 168.7 J$

b) $E_{p} = 73.6 J$

$E_{k} = 95.8 J$

$E_{m} = 169.4 J$

c) $E_{p} = 169.2 J$

$E_{k} = 0$

$E_{m} = 169.2 J$

Explanation:

We have:

m: is the ball's mass = 1.5 kg

v₀: is the initial speed = 15 m/s

g: is the gravity acceleration = 9.81 m/s²

a) In the initial position we have:

h: is the height = 0

The potential energy is given by:

$E_{p} = mgh = 0$

The kinetic energy is:

$E_{k} = \frac{1}{2}mv^{2} = \frac{1}{2}*1.5*(15)^{2} = 168.7 J$

And the mechanical energies:

$E_{m} = E_{p} + E_{k} = 0 + 168.7 J = 168.7 J$

b) At 5 m above the initial position we have:

h = 5 m

The potential energy is:

$E_{p} = mgh = 1.5*9.81*5 = 73.6 J$

Now, to find the kinetic energy we need to calculate the speed at 5 m:

$v_{f}^{2} = v_{0}^{2} - 2gh = (15)^{2} - 2*9.81*5 = 126.9$

$v_{f} = \sqrt{126.9} = 11.3 m/s$

$E_{k} = \frac{1}{2}mv^{2} = \frac{1}{2}*1.5*(11.3)^{2} = 95.8 J$

And the mechanical energies:

$E_{m} = E_{p} + E_{k} = 73.6 + 95.8 J = 169.4 J$

c) At its maximum height:

$v_{f}$ : is the final speed = 0

$h = \frac{v_{0}^{2}}{2g} = \frac{(15)^{2}}{2*9.81} = 11.5 m$

Now, the potential, kinetic and mechanical energies are:

$E_{p} = mgh = 1.5*9.81*11.5 = 169.2 J$

$E_{k} = \frac{1}{2}mv^{2} = 0$

$E_{m} = 169.2 J + 0 = 169.2 J$

I hope it helps you!

7 0

3 years ago

Which of the following is an example of heat being transferred by radiation? Choose all that apply, Fire, Sun, Candle Flame, Sto

OlgaM077 [116]

Answer:

Fire, Sun, Candle Flame, Stove

4 0

3 years ago

Read 2 more answers

How fast can the 140 a current through a 0.200 h inductor be shut off if the induced emf cannot exceed 80.0 v?

Vesna [10]

Recall that to compute for the emf of a circuit given current and inductance, we must recall that

$emf = - M \frac{\Delta I }{\Delta t}$

where I is the current (A), M is the mutual inductance (h), and t is the time (ms). Since the current must not exceed 80.0 V, we have

$80.0 \geq 0.200(\frac{140}{t})$
$t \geq \frac{28.0}{80}$
$t \geq 0.35$

From this, we see that it must take at least 0.35 ms so it doesn't exceed 80 V.
Answer: 0.35 ms

7 0

3 years ago

A sample of an unknown substance has a mass of 0.465 kg. if 3,000.0 j of heat is required to heat the substance from 50.0°c to 1

hammer [34]

The specific heat of the substance will be 0.129 J/g°C.

<h3>What is specific heat capacity?</h3>

The amount of heat required to increase a substance's temperature by one degree Celsius is known as specific heat capacity.

Similarly, heat capacity is the relationship between the amount of energy delivered to a substance and the increase in temperature that results.

The given data in the problem is;

Q is the amount of energy necessary to raise the temperature = 3,000.0 j

M is the mass= 0.465 kg.

Δt is the time it takes to raise the temperature.=50°c

s stands for specific heat capacity=?

Mathematically specific heat capacity is given by;

$\rm Q= MC \triangle t \\\\ C = \frac{Q}{M\triangle t} \\\\ C = \frac{3000}{0.465 \triangle 50} \\\\ C =129.0 J/Kg^0C \\\\ C= 0.129 J/g^0C$

Hence the specific heat of the substance will be 0.129 J/g°C.

To learn more about the specific heat capacity refer to the link brainly.com/question/2530523

5 0

2 years ago

Which of the following is not an example of centripetal acceleration?

Amanda [17]

An apple falling to the ground is not an example of centripetal acceleration.

5 0

3 years ago