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Alona [7]
4 years ago
11

Suppose a star the size of our Sun, but with mass 9.0 times as great, were rotating at a speed of 1.0 revolution every 7.0 days.

If it were to undergo gravitational collapse to a neutron star of radius 13 km , losing three-quarters of its mass in the process, what would its rotation speed be
Physics
1 answer:
kvasek [131]4 years ago
3 0

Answer:

Its rotation will be 3.89x10⁴ rad/s.

Explanation:

We can find the rotation speed by conservation of the angular momentum:

L_{i} = L_{f}

I_{i}\omega_{i} = I_{f}\omega_{f}   (1)

The initial angular speed is:

\omega_{i} = \frac{1 rev}{7 d} = 0.14 \frac{rev}{d}

The moment of inertia (I) of a sphere is:

I = \frac{2}{5}mr^{2}    (2)

Where m is 9 times the sun's mass and r is the sun's radius

By entering equation (2) into (1) we have:

\frac{2}{5}m_{i}r_{i}^{2}\omega_{i} = \frac{2}{5}m_{f}r_{f}^{2}\omega_{f}

9m_{sun}(696342 km)^{2}0.14\frac{rev}{d} = \frac{3}{4}9m_{sun}(13 km)^{2}\omega_{f}

\omega_{f} = \frac{4}{3}*0.14 \frac{rev}{d}(\frac{696342 km}{13 km})^{2} = 5.36 \cdot 10^{8} \frac{rev}{d}*\frac{1 d}{24 h}*\frac{1 h}{3600 s}*\frac{2\pi rad}{1 rev} = 3.89 \cdot 10^{4} rad/s          

Hence, its rotation will be 3.89x10⁴ rad/s.

I hope it helps you!                                                        

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If a 20 g cannonball is shot from a 5 kg cannon with a velocity of 100
balu736 [363]

Strange as it may seem, the statement in the question appears to be <em>TRUE</em>.  

-- Before the shot, neither the cannon nor the ball is moving, so their combined momentum is zero.  

-- Since momentum is conserved, we know immediately that their combined momentum AFTER the shot also has to be zero.

-- (20g is rather puny for a "cannonball" ... about the same weight as four nickels. But we'll take your word for it and just do the Math and the Physics.)

-- Momentum = (mass) x (velocity)

After the shot, the momentum of the cannonball is

(0.02 kg) x (100 m/s ==> that way)

Momentum of the ball = 2 kg-m/s ==> that way.

-- In order for both of them to add up to zero, the momentum of the cannon must be (2 kg-m/s this way <==) .

Momentum of cannon = (5 kg) x (V m/s this way <==)

2 kg-m/s this way <== = (5 kg) x (V m/s this way <==)

Divide each side by (5 kg):

V m/s  =  (2/5) m/s this way <==

Speed of recoil of the cannon = <em>-- 0.4 m/s</em>

3 0
3 years ago
A proton moving at 3.0 × 10^4 m/s is projected at an angle of 30° above a horizontal plane. If an electric field of 400 N/C is a
GuDViN [60]

Answer:

The time it takes the proton to return to the horizontal plane is 7.83 X10⁻⁷ s

Explanation:

From Newton's second law, F = mg and also from coulomb's law F= Eq

Dividing both equations by mass;

F/m = Eq/m = mg/m, then

g = Eq/m --------equation 1

Again, in a projectile motion, the time of flight (T) is given as

T = (2usinθ/g) ---------equation 2

Substitute in the value of g into equation 2

T = \frac{2usin \theta}{\frac{Eq}{m}} =\frac{m* 2usin \theta}{Eq}

Charge of proton = 1.6 X 10⁻¹⁹ C

Mass of proton = 1.67 X 10⁻²⁷ kg

E is given as 400 N/C, u = 3.0 × 10⁴ m/s and θ = 30°

Solving for T;

T = \frac{(1.67X10^{-27}* 2*3X10^4sin 30}{400*1.6X10^{-19}}

T = 7.83 X10⁻⁷ s

6 0
3 years ago
Daltons theory was identified using
Margaret [11]
<h2>Answer with Explanation </h2>

Dalton’s theory can be classified by the following hypotheses:

1) All material was formed of particles, unbreakable and strong construction segments.

2) All particles of a given component are indistinguishable in volume and characteristics

3) Compounds are determined by a mixture of two or more distinct kinds of atoms.

4) Chemical responses appeared in the rearrangement of the reacting atoms.

This theory was to explain all matter in terms of atoms and their characteristics, the law of conservation of volume and the law of constant composition.

7 0
3 years ago
Wtz the answer to this question? I need to get it right
Rama09 [41]

Answer: Next time you create a question, add an image or PDF. Because I do not know the question. So, may you please create a new question?

4 0
3 years ago
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What is the kinetic energy of an object that has a mass of 12 kg and moves with a velocity of 10 m/s
WITCHER [35]

Answer:

600 J

Explanation:

The formula to find the kinetic energy of an object is \frac{1}{2}mV^2

  • m = mass in kg
  • V = velocity in m/s
  • KE is measured in Joules just as all other forms of energy.

Now, let's plug in the variables we're given and simplify.

  • \frac{1}{2}(12)(10)^2
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  • (6)(100)
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Thus, the answer is 600 Joules.

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