cepheid stars are useful to astronomers as indicators of group of answer choices white-dwarf star behavior. the mechanics of eclipsing variable stars. distance, particularly to stars in our galaxy and to nearby galaxies. stars with very high speed motion.

Answer:

true

Explanation:

Beyond "c", the speed of the rocket is; (D) increasing for a while and constant thereafter.

The space shuttle must accelerate from zero to 8,000 metres per second (nearly 18,000 miles per hour) in eight and a half minutes to reach the minimum height necessary to circle the Earth.

The orbital velocity is 7.9 kilometres per second, which translates to more than 20 times the speed of sound. A rocket attaining orbital velocity (1st cosmic velocity) will enter orbit around the Earth (C), whereas a faster rocket would follow an elliptical trajectory (D).

On Earth, air tends to prevent exhaust gases from exiting the engine. This lessens the thrust. However, because there is no atmosphere in space, the exhaust gases may depart considerably more easily and quickly.

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The time taken for the rocket to reach a speed of 2430m/s from rest is 27.0 seconds.

Motion is simply the change in position of an object over time.

From the First Equation of Motion;

v = u + at

Where v is final velocity, u is initial velocity, a is acceleration and t is time elapsed.

Given the data in the question;

To determine the time, substitute the given values into the formula above and solve for t.

v = u + at

2430m/s = 0 + ( 90m/s² × t )

2430m/s = 90m/s² × t

t = 2430m/s / 90m/s²

t = 27.0s

Therefore, the elapsed time is 27.0 seconds.

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A rocket launched with an acceleration of 90 m/s², and a final speed of 2430 m/s. So the time required to reach the final speed is 27 seconds.

The ratio of change in velocity to time is referred to as acceleration. It has a SI unit m/s² with dimension formula MLT⁻².

According to the question, the given values are,

Final velocity, v = 2430 m/s

Initial velocity, u = 0 m/s

The acceleration is given as, a = 90 m/s².

Use the equation of motion to find the time required to reach the final speed,

v = u + at

2430 = 0 + ( 90 × t )

2430 = 90 × t

t = 2430 / 90

t = 27.0 seconds.

Hence, the time taken to reach the final speed is 27 seconds.

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An elliptical galaxy is a galaxy with an elliptical outline and a smooth distribution of brightness (no spiral arms).

In the field of astronomical physics, we can describe elliptical galaxies as stretched galaxies that have an elliptical outline. This type of galaxy is usually made through old stars and has an even, smooth distribution of light.

Although the elliptical galaxies are not a major part of the universe they make up 10–15% in the Virgo Supercluster.

As the elliptical galaxy is made from broken stars, their size may vary from being a dwarf elliptical to a supergiant.

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535.1 Newton Force is the magnitude of the acceleration of the chair.

Fnet=Fp×cos35-F

=164×cos35-91

=43.34 N

a=Fnet/m

=43.34/45

=0.963 m/s^2

FN = mg + Fp×sin35

=45×9.8+164×sin35

=535.1 N

Newton is the abbreviation for the SI unit of absolute force known as newton (N). It is described as the amount of force required to accelerate a kilogram of mass by one meter per second. In the foot pound second system, one newton is equivalent to around 0.2248 pounds of force or 100,000 dyne in the centimeter gram second (CGS) system. The newton was given its name in  of Sir Isaac Newton, whose second rule of motion outlines the modifications that a force may cause in a body motion.

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When a mass attached to a spring, it will make the spring to produce a harmonic motion with frequency 1.4 Hz. Then the mass is 77.48 gram.

The frequency of a harmonic motion caused by a displaced spring is:

f = 1/2π . √(k/m)

Where:

k = spring constant

m = mass

Parameters given from the problem:

f = 1.4 Hz

k = 6 N/m

Plug those parameters into the formula:

1.4 = 1/2π . √(6/m)

√(6/m) = 8.8

m = 0.07748 kg = 77.48 gram

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Both cylinders will reach the same speed since speed is independent of mass and radius.

Radius of smaller cylinder = R1

Radius of bigger cylinder = R2

their masses = m1/m2 =  [tex]\frac{R1}{2R1} ^{2}[/tex]

From law of conservation of energy we have

[tex]mv^{2} /2 + Iw^{2}[/tex] = mgh

[tex]1/2 mv^{2}[/tex] + [tex]m\frac{R}{L}[/tex] × [tex]\frac{x}{y}[/tex] =  mgh

3/4 v2 = gh

v= [tex]\sqrt{4/3gh}[/tex]

Since from the above relation, speed is independent of mass and radius, so both cylinders have same speed.

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Neither of the two cylinders moves faster at the bottom. Both cylinders move with the same velocity at the bottom.

By the formula for conservation of energy, for a solid cylinder placed at the top of a ramp and rolling down to the bottom, we have

The kinetic energy of linear motion + rotational kinetic energy = potential energy                    (1)

Kinetic energy due to linear motion (of the center of mass of cylinder)= [tex]\frac{1}{2} mv^{2}[/tex]

Rotational kinetic energy = [tex]\frac{1}{2}Iw^{2}[/tex]

m = mass of cylinder, v = velocity of the center of mass of the cylinder

I = moment of inertia of solid cylinder = [tex]\frac{1}{2}mR^{2}[/tex]      (R = radius of cylinder)

angular velocity w = v/R  

g = acceleration due to gravity, h= height of the ramp

From equation (1)

[tex]\frac{1}{2}mv^{2}+ \frac{1}{2}Iw^{2} = mgh[/tex]

⇒[tex]\frac{1}{2}mv^{2}+\frac{1}{2}(\frac{1}{2}mR^{2}* \frac{v^{2} }{R^{2} } ) = mgh[/tex]

⇒[tex]\frac{1}{2}mv^{2}+\frac{1}{4}mv^{2}=mgh[/tex]

⇒[tex]\frac{3}{4}[/tex][tex]mv^{2} =mgh[/tex]

⇒v=√(4gh/3)              (cancel m on both sides)

Thus we see the velocity at the bottom of the sloping ramp that is v is independent of the mass or radius of the solid cylinders and only depends on the height of the ramp and acceleration due to gravity.

Thus both cylinders reach the bottom with the same velocity.

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We will have that the power will be:

So, the power was 220 Watts.

Answer:

30.95 cm

Explanation:

The focal length f, the object distance do, and the image distance di are related with the following equation:

So, replacing the values, we get:

Then, solving for di, we get:

Therefore, the image distance is 30.95 cm

Answer:

25000Nm⁻² using rounded g figure

Explanation:

The box is in cm. It needs to be converted into SI metres.

1m = 100cm

1cm = ( 1 / 100 )m

2cm = ( 1 / 50 )m

A = ( 1 / 2500 )m²

Assume that g = 10ms⁻¹. Use your own definition.

F = 10N

P = F / A

P = 10N( 2500 )m⁻²

25000Nm⁻²

Answer:

Explanation:

Given:

m = 2 kg

a = 2 cm = 0.02 m

g =9.8 m/s²

_______________

P - ?

Area of the cube:

S = a² = 0.02² = 0,0004 m²

Gravity:

F = m·g = 2·9.8 = 19.6 N

Pressure:

p = F / S =  19.6 / 0,0004 = 49 000 N/m²

The correct answer is option C:

According to modern ideas and observations, the location of the center of our expanding universe explains that the universe does not have a center.

Our universe is composed of three kinds of substances that are dark matter, normal matter, and dark energy.

Everything in the universe is made of normal matter i.e. planets, stars, human beings, and all other visible objects.

Astronomers have theorized that the universe is expanding at a faster rate. Between any two given points, the distance of the universe is increasing and so we can predict that the universe will be 2x in size after ten billion years.

In general, the universe has no central point and it is expanding continuously because of a dark, mysterious force that is pulling the universe apart.

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120N  is the force of gravity pulling on a 12kg block accelerating at 10m/s²

F = m × a

F = 10 ×12

F= 120N

The mass (m) and height (h) of the item determine how much gravitational potential energy is there. Based on an object's high position relative to a lower location, gravitational energy is potential energy that is stored in the object.

This energy can be utilised later to move an item since it can be stored and utilised at a later time. Three variables—mass, gravity, and height—determine the gravitational potential energy. Energy is directly inversely proportional to all three variables.

Because the highest amount of energy that may be converted into other forms is called potential energy. You need more energy to move the thing at a greater height.

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The coefficient of static friction between the ramp of 75 cm horizontal length and a vertical length of 19 cm and object with a mass of 128 g is 0.25

Since the ramp forms a right angled triangle,

tan θ = Opposite side / Adjacent side

Opposite side = Vertical length of ramp = 19 cm

Adjacent side = Horizontal length of ramp = 75 cm

tan θ = 19 / 75

θ = [tex]tan^{-1}[/tex] ( 0.25 )

θ = 14°

m = 128 g = 0.128 kg

g = 9.8 m / s²

W = m g

W = 0.128 * 9.8

W = 1.25 N

Since the object is in static condition,

∑ [tex]F_{y}[/tex] = 0

N - [tex]W_{y}[/tex] = 0

N - W cos θ = 0

N = 1.25 * cos 14°

N = 1.25 * 0.97

N = 1.21 N

F[tex]_{s}[/tex] = μ[tex]_{s}[/tex] N

F[tex]_{s}[/tex] = Static frictional force

μ[tex]_{s}[/tex] = Co-efficient of static friction

N = Normal force

Since the object is in static condition,

∑ [tex]F_{x}[/tex] = 0

F[tex]_{s}[/tex] - [tex]W_{x}[/tex] = 0

F[tex]_{s}[/tex] = W sin θ

F[tex]_{s}[/tex] = 1.25 * sin 14°

F[tex]_{s}[/tex] = 1.25 * 0.24

F[tex]_{s}[/tex] = 0.3 N

μ[tex]_{s}[/tex] = F[tex]_{s}[/tex] / N

μ[tex]_{s}[/tex] = 0.3 / 1.21

μ[tex]_{s}[/tex] = 0.25

Therefore, the coefficient of static friction between the ramp and object is 0.25

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Answer:

100 m

Explanation:

5  m/s   *   20 s = 100 m

Answer:

Approximately [tex]0.388\; {\rm s}[/tex], assuming that air resistance is negligible and that [tex]g = 9.81\; {\rm m\cdot s^{-2}}[/tex].

Explanation:

Initial vertical velocity of the object: [tex]u = 11.0\; {\rm m\cdot s^{-1}}[/tex], upwards (same as that of the rollercoaster.)

Initial height of the object: [tex]h_{0} = 5.00\; {\rm m}[/tex].

If air resistance is negligible, this object will accelerate downwards at a constant [tex]a = (-g) = (-9.81)\; {\rm m\cdot s^{-2}}[/tex]. Note that [tex]a[/tex] is negative since the object is accelerating downwards.

The SUVAT equation [tex]h = (1/2)\, a\, t^{2} + u\, t + h_{0}[/tex] gives the height [tex]h[/tex] of this object at time [tex]t[/tex]. Note that while the initial height is [tex]5.00\; {\rm m}[/tex], [tex]h = 0[/tex] when the object reaches the ground.

Since acceleration [tex]a[/tex], initial velocity [tex]u[/tex], and initial height [tex]h_{0}[/tex] are all given, setting [tex]h\![/tex] to [tex]0[/tex] and solving for [tex]t[/tex] will give the time it takes for this object to reach the ground:

[tex](1/2)\, a\, t^{2} + u\, t + h_{0} = 0[/tex].

[tex](1/2)\, (-9.81) \, t^{2} + 11.0\, t + 5.00 = 0[/tex].

[tex](-4.905)\, t^{2} + 11.0\, t + 5.00 = 0[/tex].

Solve this equation for [tex]t\![/tex] using the quadratic formula. Note that [tex]t > 0[/tex] since [tex]t[/tex] denotes the amount of time required for the object to reach the ground.

[tex]\begin{aligned} t &= \frac{-11.0 + \sqrt{11.0^{2} - 4 \times (-4.905) \times 5.00}}{2\times (-4.905)} \\ &\approx 0.388\; {\rm s}\end{aligned}[/tex].

The other root of this quadratic equation is negative and isn't a valid solution to the question.

In other words, it will take approximately [tex]0.388\; {\rm s}[/tex] for this object to reach the ground.

The first and second blocks move at the same speed.

What is the law of conservation of mechanical energy ?

The law of conservation of mechanical energy states that the total mechanical energy of a system is constant if the only forces acting on the system are conservative.

The total mechanical energy of a system is the sum of kinetic and potential energy.

E = KE + PE

This is the total energy, kinetic energy and potential energy of the system.

The kinetic energy of the

system is:

KE = 1/2 x m x v^{2}

This is the mass and velocity of the object.

The gravitational potential energy is:

PE = mgh

Here is the acceleration of gravity and altitude.

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Bring mass up against the axis of rotation. Consequently, a rotating object's overall moment of inertia will decrease due to its mass. The axis and the mass narrows as the mass moves closer together.

A measure of a body's propensity to resist angular acceleration that is calculated by summing the products of each particle's mass and square of its distance from the axis of rotation moment of inertia

A line along which an item rotates is referred to as its axis of rotation (also known as its axis of revolution). That line is typically fictitious in physics and calculus. The distance from the object's outside border to the axis of rotation is known as the radius of rotation.

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The energy of the photon of light as we can see here is 2.9 * 10-19 J.

We know that light has to do with any of the components of the electromagnetic spectrum. These are the kinds of radiation that are able to pass through vacuum because they do not need a medium for the propagation of the wave. We are now asked to obtain the energy of the photon based in the wavelength that we have been supplied in the question here.

We have that the wavelength of the photon from what we can see in the question have been given as 670 nm. Then;

E = hc/λ

E = energy of the light

h = Plank's constant

c = speed of light

λ = wavelength of the light

It then follows that;

E = 6.6 * 10^-34 * 3 * 10^8/670 * 10^-9

E = 2.9 * 10-19 J

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The time required to gain the thermal energy is 3465/P second.

We need to know about thermal energy to solve this problem. The total heat received by the system will equal to total heat released by objects. It should follow

Q released = Q received

The heat can be defined by

Q = m . c . ΔT

where Q is thermal energy, m is mass, c is the specific heat constant and ΔT is the change in temperature.

The given parameters are

m = 25 g = 0.025 kg

c = 4200 J/kgK

ΔT = 60 ⁰C - 27 ⁰C = 33 ⁰C

The thermal energy released by the heating element per second is equal to the power. Let's assume that the heating element has the power of P

Find the thermal energy received by the water

Q = m . c . ΔT

Q = 0.025 . 4200 . 33

Q = 3465 joule

Find the time required to raise the temperature

P = Q / t

P = 3465 / t

t = 3465 / P second

where P is power in the watt unit.

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The speed of the two players after the collision is 0.31 m/s in a direction of due south.

The final speed of the two players after the collision is calculated as follows.

Apply the principle of conservation of linear momentum;

m₁u₁ + m₂u₂ = v(m₁ + m₂)

where;

(70 x 5.5) + (-110 x 4) = v(70 + 110)

385 - 440 = 180v

-55 = 180v

v = -55/180

v = -0.31 m/s

Thus, the direction of the speed of the two players after the collision is due south.

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The magnitude of the average force exerted by the seat belt on the dummy is 224N .

The average force is the force produced by an object moving over a specific period of time at a given rate of speed, or velocity. This velocity is not instantaneous or precisely measured, as the word "average" indicates.

mass of the dummy (m) = 80kg

velocity of the dummy (v) = 28 m/s

time (t) = 10 seconds

Average force exerted (F)

To calculate the average force;

According to the formula;

F = (m × v) ÷ t

Where;

F represents the force exerted

m represents the mass of the dummy

v represents the velocity

t represents the time

F = m * v/t

F = 80 *28/10

F = 224

F = 224 N

The force exerted by the seat belt on the dummy is 224N .

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Apply:

C = A e0 / d

Where:

C = capacitance = 1pf = 1 x10^-12 F

A = area

ε0 = 8.85×10^-12

1 pf = 1 x 10^-12 F

A = Cd / ε0 = 1 x 10^-12 ( 1 x 10^-4 ) / 8.85×10^-12 = 1.13 x10 ^-5 m^2

The nut distance from the Bullwinkle after uniform motion is 21 m.

We need to know about the uniform motion to solve this problem. The uniform motion is an object's motion under acceleration. It should follow the rule

vt = vo + a . t

vt² = vo² + 2a . s

s = vo . t + 1/2 . a . t²

where vt is final velocity, vo is initial velocity, a is acceleration, t is time and s is displacement.

From the question above, the parameters given are

m = 0.5 kg

s = 15 m

vx = 12 m/s

vo = 0 m/s

a = g = 9.8 m/s²

Find the time taken of the nut for landing

s = vo . t + 1/2 . a . t²

15 = 0 + 1/2 . 9.8 . t²

t² = 3.06

t = 1.75 s

Find the distance of nut in horizontal direction

vx = x / t

12 = x / 1.75

x = 12 . 1.75

x = 21 m

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Answer:

C Volume

Explanation:

You would use a graduated cylinder with liquid in it to see how much is displaced when the object is placed in it to determine the volume of the object

The angular acceleration of the beam of length 2 meters and mass 5 kg is 240 radian/s².

The length of the rod is 2 meters, the mass of the rod is 5kg, a force of 200N is applied downward in the east direction while a force of 200N applied upward in west direction.

We know,

That the torque on a body is,

T = Fr

T is torque,

F is the force,

r is the perpendicular distance from the axis of rotation.

So, assuming the centre of the beam as the axis of rotation, the torque on the body is,

T = 200(1)+200(1)

T = 400N-m

We also know,

That torque on the body is,

T = IA

Where I is moment of inertia of the beam,

A is the angular acceleration of the body,

We know, moment of inertia of the beam assuming the centre of the rod as axis of rotation is,

I = MR²/12

M is the mass of the body,

R is the length of the rod,

So,

I = 5(2)²/12

I = 20/12 kg-m²

So, now we can write,

T = 20/12A

As both are value of torque, so,

20/12A = 400

A = 240 radian/s²

The angular acceleration is 240 radian/s².

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Answer: Most consistent of all elements (if consistency here denotes stability)

if not, then the answer will be (D)

Explanation:

Nobel gasses have full outermost electron shells which means that they are very stable and do not need to lose, gain, or share electrons to gain stability. So they do not react with other elements to form ionic or covalent bonds

The ball experiences an equal and opposing force from the wall as a result of Newton's third law .Therefore, in a perfect world, the ball would return at the same speed it originally did, preserving momentum.

   explain magnitude of the loss in the Kinetic energy?

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the answer to this is finishing