When a star like our sun runs out of nuclear fuel, it collapses to a white dwarf star the size of the Earth, but with the same mass the star had before the collapse. If a star initially rotates once every 25 days, like our sun, what will its rotation rate be after it becomes a dwarf
Answer:
T = 1.8 10² s
Explanation:
This is an exercise of conservation of angular momentum,
Initial instant. Before collapsing
L₀ = I₀ w₀
Final moment. After the collapse
L_f = I w
as the system is isolated, the moment is conserved
L₀ = L_f
I₀ w₀ = I w
w = [tex]\frac{I_o}{I} \ w_o[/tex]
indicates that the rotation period is 25 day, let's reduce to the SI system
T = 25 day (24 h / 1 day) (3600 s / 1 h) = 2.16 10⁶ s
Angular velocity and period are related
w = 2π/ T
The moment of inertia of a sphere is
I = 2/5 M R ²
in this case the moment before and after the collapse is
I₀ = 2/5 M R₀²
I = 2.5 M R²
the radius of a star like the sun is
R₀ = 6.96 10⁸ m
the radius of the earth
R = 6.371 10⁶ m
we substitute
w = [tex]\frac{I_o}{I} \ w_o[/tex]
[tex]\frac{2\pi }{T} =( \frac{R_o}{R} )^2 \ \frac{2\pi }{T_o}[/tex]
T = ([tex]\frac{R}{R_o}[/tex] )² T₀
let's calculate
T = (6.371 10⁶ / 6.96 10⁸ )² 2.16 10⁶
T = 1.8 10² s
how does energy apply to newton’s laws?
Answer:
the acceleration of an object is directly pro to the net force acting on it and indirectingly proportional to its mass
Pls help me...
..............
Explanation:
The graphs show maximum gravitational potential energy for the pendulum and they correspond to positions #1 and #5.
a vibrating source with a frequency of 20.0Hz produces water waves that have a wavelength of 3.0 cm. Calculate the speed of the waves 
Answer:
60m/s
Explanation:
v=frequency ×wave length
v signifies the speed
The speed of a wave is the product of its frequency and wavelength. Hence the speed of the wave with a frequency of 20 Hz and 30 cm wavelength is 0.6 m/s.
What frequency?Frequency of a wave is the number of wave cycles produced at unit time. Thus it has the unit of s⁻¹ which is equivalent hertz Hz.
Wavelength of a wave is the distance it travels in a wave cycle or for a transverse wave the distance between two consecutive crests or troughs is called wavelength.
The relation between frequency v, wavelength [tex]\lambda[/tex] and speed of a wave c is written as below:
[tex]c = v \lambda[/tex]
By this expression it is clear that the speed of increases with frequecy and wavelength.
The frequency of the given vibrational source is 20 Hz and the wavelength is 3 cm or 0.03 m. Hence, the speed of the wave is calculates as follows:
c = 20 Hz × 0.3 m
= 0.6 m/s.
Therefore, the speed of the wave is 0.6 m/s.
To find more on wavelength, refer here:
https://brainly.com/question/4112024
#SPJ2
How much (in newtons) does a 15-kg bag of feathers weigh? Show work
Here's the solution :
we know,
[tex] \boxed{weight = m \times g}[/tex]
where,
m = mass of the objectg = acceleration due to gravityso,
[tex]w = 15 \times 9.8[/tex][tex]w = 147 \: \: \: newtons[/tex]Put these components from largest to smallest
1. comet
2. star
3. galaxy
4. nebula
5. planet
6. universe
Answer:
6, 3, 2, 5, 4, 1
Explanation:
Let's describe them from smallest to largest. In fact the size order is not exact as there are exceptions.
An asteroid is a rocky body which lies in the asteroid belt between Mars and Jupiter. They are typically quite small object. The largest asteroid Ceres has been reclassified as a dwarf planet.
A moon is typically a rocky body which is in orbit around a planet. Some moons such as our Moon are quite large and are typically bigger than asteroid. Some moons can actually be smaller than some asteroids.
A planet is a nearly spherical body which is in orbit around the Sun. Planets are larger than moons.
A star is what planets orbit around. It is the source of light and heat. Our Sun is a star which is many times bigger than all of the planets.
A solar system is a star and all of its planets, asteroids, comets and other bodies. It is significantly bigger than a star.
A galaxy, such as our Milky Way Galaxy, is a collection of solar systems orbiting around a central core. Most galaxies have a supermassive black hole at their centres.
Galaxies also form clusters which are large scale structures.
The universe is everything. It contains billions of galaxies.
Your family is on a vacation at the coast and is spending the day at the beach. Your brothers are setting up the umbrellas and beach chairs for the day. You notice that since the tide is low, they are setting everything up close to the water’s edge. Is this a good idea? Explain.
When 685 J of thermal energy (heat) is added to 7.9 g of a substance at 31°C, the temperature increases from 31 °C to 98 °C. What is the specific heat of the substance?
Answer:
Specific heat capacity, = 1.2942 J/g°C
Explanation:
Given the following data;
Heat capacity = 685 J
Mass = 7.9 g
Initial temperature = 31°C
Final temperature = 98°C
To find the specific heat capacity of the substance;
Heat capacity is given by the formula;
[tex] Q = mcdt[/tex]
Where;
Q represents the heat capacity or quantity of heat.
m represents the mass of an object.
c represents the specific heat capacity of water.
dt represents the change in temperature.
dt = T2 - T1
dt = 98 - 31
dt = 67°C
Making c the subject of formula, we have;
[tex] c = \frac {Q}{mdt} [/tex]
Substituting into the equation, we have;
[tex] c = \frac {685}{7.9*67} [/tex]
[tex] c = \frac {685}{529.3} [/tex]
Specific heat capacity, = 1.2942 J/g°C
Blue light bends more than red light when it passes through glass. Thus, blue light has a greater
A. angle of refraction
B. interference pattern
C. index of refraction
E. wavelength
Answer:
I think c is the correct answer
Answer: C
Explanation:
In the diagram, R1 = 40.0 ,
R2 = 25.4 Q, and R3 = 70.8 Q. What is
the equivalent resistance of the group?
Reg = [ ? ]
(And none of those links please)
Answer:
51 Ω.
Explanation:
We'll begin by calculating the equivalent resistance of R₁ and R₃. This can be obtained as follow:
Resistor 1 (R₁) = 40 Ω
Resistor 3 (R₃) = 70.8 Ω
Equivalent Resistance of R₁ and R₃ (R₁ₙ₃) =?
Since the two resistors are in parallel connection, their equivalent can be obtained as follow:
R₁ₙ₃ = R₁ × R₃ / R₁ + R₃
R₁ₙ₃ = 40 × 70.8 / 40 + 70.8
R₁ₙ₃ = 2832 / 110.8
R₁ₙ₃ = 25.6 Ω
Finally, we shall determine the equivalent resistance of the group. This can be obtained as follow:
Equivalent Resistance of R₁ and R₃ (R₁ₙ₃) = 25.6 Ω
Resistor 2 (R₂) = 25.4 Ω
Equivalent Resistance (Rₑq) =?
Rₑq = R₁ₙ₃ + R₂ (series connection)
Rₑq = 25.6 + 25.4
Rₑq = 51 Ω
Therefore, the equivalent resistance of the group is 51 Ω.
I put the screenshot below.
Answer:
1-a
2-d
3-c
4-b
Explanation:
i tookt he words and put it in the sentance and these made most sence to me
Complex matching suggests that individuals who have formed a relationship may differ predominantly in the area of __________.
Answer:
physical attractiveness
Explanation:
A small cork with an excess charge of +6.0 µC is placed 0.95 m from another cork, which carries a charge of -4.3 µC. What is the magnitude of the electric force between them?
Answer:
F = 0.257 N
Explanation:
The magnitude of the electric force between the charges can be calculated by using Colomb's Law:
[tex]F = \frac{kq_1q_2}{r^2}[/tex]
where,
F = Electric Force = ?
k = Colomb's Constant = 9 x 10⁹ Nm²/C²
q₁ = charge on first cork = 6 μC = 6 x 10⁻⁶ C
q₂ = charge on second cork = 4.3 μC = 4.3 x 10⁻⁶ C
r = distance between corks = 0.95 m
Therefore,
[tex]F = \frac{(9\ x\ 10^9\ N.m^2/C^2)(6\ x\ 10^{-6}\ C)(4.3\ x\ ^{-6}\ C)}{(0.95\ m)^2}[/tex]
F = 0.257 N
A student is constructing an investigation on static electricity. The student has three balloons and rubs two of them on a piece of wool. The student then touches each balloon to the wall to observe if static electricity would cause the balloon to stick. What is the independent variable in this investigation.
Answer:
Explanation:
As given, the student has three balloons and rubs two of them on a piece of wool. The rubbing of balloon on wool is the independent variable as it was done on two and not on the third as control.
I need help?? Plz help me
Answer:
12. b
13. a
Explanation:
When responding to sound, the human eardrum vibrates about its equilibrium position. Suppose an eardrum is vibrating with an amplitude of 7.2 x10-7 m and a maximum speed of 3.6 x10-3 m/s. (a) What is the frequency (in Hz) of the eardrum's vibrations
Answer:
796.18 Hz
Explanation:
Applying,
Maximum velocity = Amplitude×Angular velocity
Therefore,
V' = A(2πf)............... Equation 1
Where V' = maximum velocity of the eardrum, A = Amplitude of vibration of the eardrum, f = frequency of the eardrum vibration, π = pie
make f the subject of the equation
f = V'/2πA................ Equation 2
From the question,
Given: V' = 3.6×10⁻³ m/s, A' = 7.2×10⁻⁷ m,
Constant: 3.14.
Substitute these values into equation 2
f = 3.6×10⁻³/( 7.2×10⁻⁷×2×3.14)
f = 796.18 Hz
why is it not possible to make use of solar cells to meet all of our energy needs?why
Answer:
In the solar cells, the energy is obtained only during the day, when the Sun shines. .So, it increases the cost of using solar panels as the source of energy. So, the solar cell is not used to meet all our energy needs
hope this helps
have a good day :)
Explanation:
Answer:
In the solar cells, the energy is obtained only during the day, when the Sun shines. ... So, it increases the cost of using solar panels as the source of energy. So, the solar cell is not used to meet all our energy needs
Explanation:
n the solar cells, the solar panel convert solar energy into electricity, which is stored in storage battery. The storage battery give the direct current but all the appliances are working by the alternating current, so first of all direct current is converted into alternating current by any suitable appliances before it can be used to run various devices. So it increases the cost of using solar panels as the source of energy.
In a plate glass factory, sheets of glass move along a conveyor belt at a speed of 15.3 cm/s. An automatic cutting tool descends at preset intervals to cut the glass to size. Since the assembly belt must keep moving at constant speed, the cutter is set to cut at an angle to compensate for the motion of the glass. The glass is 73.4 cm wide and the cutter moves from one edge to the other in 3.0 s. At what angle to the width of the sheet should the cutter be set to move?
n a plate glass factory, sheets of glass move along a conveyor belt at a speed of 15.3 cm/s. An automatic cutting tool descends at preset intervals to cut the glass to size. Since the assembly belt must keep moving at constant speed, the cutter is set to cut at an angle to compensate for the motion of the glass. The glass is 73.4 cm wide and the cutter moves from one edge to the other in 3.0 s. At what angle to the width of the sheet should the cutter be set to move
Make a free-body diagram of someone pushing a refrigerator that shows:
a. A net force of 100 N with the refrigerator being pushed to the right.
b. The refrigerator is balanced on the floor.
The free body diagram allows to find the results for the forces applied on the refrigerator are;
a) Free-body diagram with applied force.
b) Free-body diagram without applied force.
A free-body diagram is a diagram of the forces without the details of the body, these diagrams are important to clearly visualize the forces and the coordinate systems against which to take measurements.
In the attached we have a free-body diagrams for a refirerator, represented by the box where the forces are appreciated:
The weight that the forces exerted by the earth on the refrigerator. The Normal which is the reaction of the earth to the support of the refrigerator. The force applied by the person. The friction force which is the force between the two surfaces that opposes the movement of the refrigerator.
Newton's second law states that the net force is proportional to the mass times the acceleration of the body.
∑ F = ma
where F is the force, m the mass and the acceleration
∑ F = F - fr = 100 N
a = 100 / m
In conclusion with the free body diagram we can find the results for the forces applied on the refrigerator are;
a) Free-body diagram with applied force.
b) Free-body diagram without applied force.
Learn more about the free-body diagram here: brainly.com/question/16799228
Can anyone help me please?
Answer:
four times the
Explanation:
...........
Electrons move towards the ________ end.
O negative
O positive
O front
O back
Answer:
they move towards the positive side... that's option 2
Which of the following is a true?
1.Energy can change from one form to another.
2.Energy can only change into heat energy.
3.Energy cannot be changed from one form to another.
Energy can be produced by 4.living things.
Answer:
please mark me as a brainleast
Explanation:
1.eneegy can change from ome form to another
It takes a crane 60 seconds to lift a 150kg box from the ground to the top of a 100m tall building. Calculate the magnitude of power exerted by the crane to lift the box
A. 9 x 109 W
B. 9 x 109 N
C. 2450 W
D. 2450 N
E. None of the above
Answer:
Explanation:
Power equals the amount of work done divided by the time it takes to do the work (in seconds). Work itself is equal to the amount of force it takes to move an object a certain number of meters. We are given the mass of the object. Since force is a measure in Newtons, and we are given mass, we need to use the mass to find the weight of the object, since weight is a force and is measured in Newtons!
F = weight = 150(9.8) so
F = 1470. Now we will use that along with the displacement in the Power equation:
P = [1470(100)]/60 so
P = 2450 Watts, choice C.
The figure below shows the apparatus used to measure the specific heat capacity of a metal. The electric heater is switched on and supplies 17 000 of thermal energy (heat) to the block of metal. The temperature of the metal rises from 16 °C to 38 °C. The mass of the block of metal is 850 g. No energy is lost from the metal. Calculate the specific heat capacity of the metal.
Answer:
0.909 J/gºC.
Explanation:
From the question given above, the following data were obtained:
Heat (Q) = 17000 J
Initial temperature (T₁) = 16 °C
Final temperature (T₂) = 38 °C
Mass (M) = 850 g
Specific heat capacity (C) =?
Next, we shall determine the change in the temperature of the metal. This can be obtained as follow:
Initial temperature (T₁) = 16 °C
Final temperature (T₂) = 38 °C
Change in temperature (ΔT)
ΔT = T₂ – T₁
ΔT = 38 – 16
ΔT = 22 °C
Finally, we shall determine the specific heat capacity of the metal. This can be obtained as follow:
Heat (Q) = 17000 J
Change in temperature (ΔT) = 22 °C
Mass (M) = 850 g
Specific heat capacity (C) =?
Q = MCΔT
17000 = 850 × C × 22
17000 = 18700 × C
Divide both side by 18700
C = 17000 / 18700
C = 0.909 J/gºC
Therefore, the specific heat capacity of the metal is 0.909 J/gºC.
the efficiency of a machine is always less than 100% because part of the energy input is used to
A. stop the machine after work
B. perform useful work on the load
C. overcome friction
D. lift the machine up
Answer:
C. Overcome Friction
Explanation:
When using any machine usually those with moving parts, you may notice heat forming near the areas where most movement occurs. As friction continues, more energy is used up and released as heat. For that reason, the efficiency of a machine will forever be less than 100%
16. A student uses 110 N of force to push a box
across a flat room for 7.2 m. Calculate the
amount of work that the student does. Round
your answer to two decimals and show the
correct units of measure.
Answer:
792J
Explanation:
Use the formula Force × Distance
With 110 newtons being the force and 7.2 meters being the distance
Which gives 792 and work us measured in joules therefore its joules
Work done is the dot product of force and displacement. The work done on the box to push across the surface for 7.2 m by applying a force of 110 N is 792 J.
What is force?Force is an external agent acting on a body tp change it from the state of motion or rest. Force is a vector quantity thus, it is characterized by a magnitude and direction.
When force acting on a body results in displacement of the body, it is said to be work done on the body. The work done on the body is the product of force and displacement.
W = F d.
Given the force acting on the box = 110 N
displacement d = 7.2 m
Work done w = 110 N × 7.2 m
= 792 J.
Therefore, the work done on the box is 792 J.
To find more on work done, refer here:
https://brainly.com/question/13662169
#SPJ2
A teacher is performing a demonstration about static electricity for his class by rubbing a balloon against a wool sweater. The balloon sticks to the wool sweater. Which particles are exchanged during the demonstration
Explanation:
the balloons which is positive looses an electron to the sweater, and the sweater which is negative gains the electron
Static charge is developed within a body temporarily with an induced polarization. Electrons are exchanged from wool surface to the balloon when they rubbed against each other.
What is static electricity?When two materials rub against each other in which one to be an insulator, they will attract by the induced polarization. Rubbing causes the free electrons in the condutor to be transferred towards the insulator.
This will cause a deformation that, the random charges in the material get polarized where the electrons in the insulator will repel to the opposite pol and positive charges will align in a pole close to the condutor.
This charge separation causes the positive pole of the balloon gets attracted into the wool surface. Hence, there forms a static electricity by the passage of electron. Thus free electrons are the particles exchanged in the demonstration.
To find more on static electricity, refer here:
http://brainly.com/question/12791045
#SPJ5
2.) A red star is 55 solar radii and a white star is 52 solar radii. Which star will 1 point
appear brighter in the night sky?*
Answer:white star
Explanation:
Calculate the mass number of an atom with 8 protons, 12 neutrons and 10 electrons
Answer: 20
Explanation: Mass number is the number of neutrons plus the number of protons. 8 + 12 gives 20.
Mass number
No of protons+No of neutrons12+820Mass number is 20
An ocean wave has a frequency of 9 Hz and a speed of 18 m/s. What is the wavelength of this wave?
O 162 m
O 0.5 m
02 m
0 27 m
Answer:
The answer is 2 because the formula is
wavelength=speed/frequency