A student practicing for a cross country meet runs 250 m in 30 s. What is the average speed

The characteristics of thermal expansion allow finding that the response for a material without thermal expansion is

Thermal expansion is the macroscopic sum of the changes in the length of the bonds when the energy (temperature) changes, it can be written

              ΔL = α L₀ ΔT

Where ΔL is the change in length, α the coefficient of linear expansion, L₀ the initial length and ΔT the change in body temperature

In this case, a material is being designed that the thermal expansion is very small, for this the material must be made up of several compounds where some of them present a contraction with temperature, some examples: water at low temperature, liquefied gases , ceramic tile, quartz, etc.

The thermal expansion measurement processes control the body temperature and measure the change in length, in this case the change in length must be zero, in the attachment we can see a graph of a composite material with these characteristics, an example of this type of material is Invar an alloy of nickel and iron α = 3.7 10⁻⁶ ºC⁻¹

In conclusion, using the characteristics of thermal expansion we can find that the response of material without thermal expansion is

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Explanation:

Answer:

B

Explanation:

His law describes the orbits of planets around the Sun.

The area of astronomy that Kepler's laws address is the movement of planets within the solar system. The correct option is C.

According to Kepler's first law, "all the planets revolve in elliptical orbits around the sun, with the sun at one of the foci."

Perihelion is the point at which the planet is closest to the sun, and aphelion is the point at which the planet is farthest from the sun.

Kepler's laws of planetary motion, published between 1609 and 1619 by Johannes Kepler, describe the orbits of planets around the Sun.

Kepler's laws of planetary motion represent a watershed moment in the transition from geocentrism to heliocentrism. They establish the first quantitative link between the planets, including Earth.

Thus, the correct option is C.

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By Newton's second law, the net vertical force on the block is

∑ F = N - mg = 0

so that the normal force exerted by the surface has magnitude

N = mg = (2.52 kg) (9.80 m/s²) = 24.7 N

Then as the block slides over the surface, it feels a frictional force of

f = µ (24.7 N)

where µ is the coefficient of kinetic friction.

As the block is pushed by the spring to its equilibrium position, friction performs

µ (-24.7 N) (0.0973 m) = -2.40µ J

of work (which is negative because it opposes the block's motion).

In compressing the spring by 9.73 cm = 0.0973 m, we store

1/2 (116 N/m) (0.0973 m)² = 0.549 J

of energy. This energy is released and partially converted to kinetic energy, while the rest is lost to friction.

By the work-energy theorem, the total work performed on the block as the spring pushes it towards the equilibrium position is equal to the change in its kinetic energy:

W = ∆K

0.549 J - 2.40µ J = 1/2 (2.52 kg) v ² - 0

where v is the speed of the block at the equilibrium position. Solving for v, we get

v = 0.891 √(0.549 - 2.40µ) m/s

After the block is released, the only force acting on it as it slides freely is friction. It comes to a stop after 0.537 m, so that friction performs

µ (-24.7 N) (0.537 m) = -13.3µ J

of work.

Using the work-energy theorem again, we have

W = ∆K

-13.3µ J = 0 - 1/2 (2.52 kg) v ²

Substitute the velocity we found in terms of µ, and solve for µ :

-13.3µ J = -1/2 (2.52 kg) (0.891 √(0.549 - 2.40µ) m/s)²

===>   µ = 0.0350

Answer:

ytdgnrjjksmzjj3hfgbdhehkj jfjbcjbwbjrhrhb jdhbbjhhrhrhhjrjjr jfjnekrj

The length of his arm, L = 0.67 m.

What is time period?

A basic pendulum consists of a point mass hung by a tightly supported, weightless, and inextensible string.

T = 2π√ L/g, where L is the pendulum's length and g is the acceleration brought on by gravity, is the formula for a pendulum's period.

Given in the question  the time for 21 oscillations (complete cycles) to be 28.1 s. Assume his arm (length L) behaves as a simple pendulum, with an effective length of 2/3 L.

T = 2π√ L/g

T = 2π√2l/3g

T = 28.1/21

T = 1.33

2π√2l/3g =  1.33

l = .67 m

The length of his arm, L = 0.67 m.

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Answer:

Here is your answer,thanks for using brainly!

Explanation:

B:Molecule

Molecules usually consist of 2 atoms linked together,however some molecules  consist of thousands of atoms!

Here is a list of smalles to largest with the answers provided

Molecules

Atoms

Elements

Mixtures

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Answer:

Explanation:

T = (2π rad / rev) / (25 rad/s) = 0.251327... = 0.25 s

The propeller was turning at 25 rad/s then the period of the propeller will be equal to 0.25 seconds.

In terms of physics, velocity is a vector assessment of the motion's direction and speed. The rate of change in an object's position relative to a reference frame and time is the more precise definition of velocity. Simply put, the concept of velocity informs us of the rate at which an object is travelling in a given direction.

It indicates the rate of motion of objects. Take two moving things like our illustration. If both items are travelling in the same vague direction, it is simple to determine which is moving more quickly.

From the given data in the question,

T = 2π (rad/rev) / 25 (rad/s)

T = 0.25 seconds.

Therefore, the period of this propeller is 0.25 seconds.

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Answer:  

4.27s

Explanation:

If "t" represents the time traveled from the time rock 2 is dropped until the collision, then the time traveled for rock 1 = t + 1. And, since rock #1 is dropped making its initial velocity = 0, then:

The distance rock 1 travels is  

x = (0)(t + 1) + 1/2(-9.8)(t + 1)2 = -4.9(t2 + 2t + 1) = -4.9t2 - 9.8t - 4.9

The distance rock 2 travels  

x = -11.3t + 1/2(-9.8)t2 = -11.3t - 4.9t2

For the distances must be equal when the rocks collide:  

-4.9t2 - 9.8t - 4.9 = -11.3t - 4.9t2  

-9.8t - 4.9 = -11.3t  

-4.9 = -1.5t  

t = 3.267 s

Now, the distance they traveled can be found by plugging the 3.267 s back into either equation:

x = -11.3(3.267) - 4.9(3.267)2 = -89.2 m or 89.2 m below where they began

The time the first rock was in the air is t + 1 = 3.267 + 1 = 4.267 s = 4.27 s

Let

First rocks time be x

Second rocks time be x+1

initial velocity=u=11.3m/s

Distance of both rocks be s1 and s2

[tex]\\ \sf\longmapsto s=ut+\dfrac{1}{2}at^2[/tex]

Now

[tex]\\ \sf\longmapsto s1=11.3x+5x^2[/tex]

[tex]\\ \sf\longmapsto s2=11.3(x+1)+5(x+1)^2[/tex]

As both collide then

[tex]\\ \sf\longmapsto s1=s2[/tex]

[tex]\\ \sf\longmapsto 11.3x+5x^2=11.3x+11.3+5(x+1)^2[/tex]

[tex]\\ \sf\longmapsto 5x^2=11.3+5x^2+10x+1[/tex]

[tex]\\ \sf\longmapsto 10x+12.3=0[/tex]

[tex]\\ \sf\longmapsto x=1.23s[/tex]

Displacement

[tex]\\ \sf\longmapsto 11.3(1.23)=13.8m[/tex]

Done

The statements which are false from the choices above are:

In scenarios of like charges, the potential energy is always positive, that is because we need to put energy in the system to bring like charges closer together.

Conversely, for unlike charges, the potential energy of the pair of unlike charges is negative, as a result of the energy expended by the system in pushing the charges away from each other.

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Answer:

  1600 W

Explanation:

Power is the product of force and distance, divided by time.

  P = (120 kg)(10 m/s²)(40 m)/(30 s) = 1600 kg·m²/s³ = 1600 W

The question above wants to assess your ability to simplify complex matters. In that case, I can't answer this question for you, but I'll show you how to answer it.

First, you should research electricity and magnetism. This research will make you understand the subject and all its elements. You can do this research in textbooks and digital platforms aimed at children and teenagers since these media usually present subjects in a more simplified way.

After doing this research, you will be able to write a text about electricity and magnetism as follows:

Remember that you must use simple language, without the use of technical terms, but with common terms.

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Answer:

Special Relativity/Newtonian Physics

Explanation:

Well in Newtonian physics you could say your mass is pushing you down and the floor is pushing you up. But rather in Special relativity only to floor is pushing up on you.

In this theory the word inertial observer matters and proves several matters throughout science. So exploring is a huge important thing to do. A person cleaning the window falls, while doing so the person feel weightless while falling. Objects that fall down with the person would remain stationarily, relative to the person. Similar to a person in space. Far away from any large masses the person would be an inertial observer. With no acceleration the person is also not close to gravitational fields and all laws of physics in the person's reference frame. The man falling off the roof is an inertial observer too. Because of this both of the matters about the rocket man and the person falling off the roof are the same.But you would think that the person falling off the roof is accelerating. But the equivalence principle tells us wrong.

The equivalence principle has made it easy to prove both people in the  situations are inertial observers. People watching would think that he is accelerating, but he is not. But he is accelerating? The equivalence principle tells us to focus on the experience of the observer and the person feels weightless so they are an inertial observer. If a person in Space comes across a planet, the person's  rocket will start heading towards a planet. But the Space person would be oblivious. The person would not feel any acceleration. The spaceship would not sense any acceleration nor would it sense that it is turning. A person outside the spaceship may see the slight curving motion and the person inside would not notice until the instant it crashes into the planet. Explaining this is geodesics and spacetime it equally links and connects with this in an obvious and common way.

Spacetime is a model that makes 4D, it joins space and time, ‘Space-time’. Now people can say how it perfectly describes gravity with it’s queer way of curving.

But how does this happen without gravity? Space is 4D with width, breadth, height and time. There is a model called spacetime.  Einstein along with many other people visualise it as woven along with time. Space- time. It  curves by mass distribution. The person is still traveling in a straight line. Just straight through spacetime. It is traveling along the geodesics of spacetime.  This is actually quite common, it is just an object travelling straight on a curved surface. Like an airplane travels straight to get quicker to a different place. But it appears curved because obviously the Earth is curved. So if you unfolded the earth the path would be curved, but the plane  is  still traveling in a straight line. Let’s also say you and your friend were standing on the equator. You are 1000 kilometers  apart from your friend. As you move towards the north direction you would eventually meet with your friend. You are not being pushed by gravity but simple as that you are just traveling on the geodesics of Earth.  Matter tells spacetime how to curve, Spacetime tells matter how to move-John Wheeler.

The man falling off the roof was accelerating so what happens if the rocket man accelerates?

Now once the rocket man accelerates the floor accelerates into rocket man. Objects remain stationary but the floor also accelerates into the objects. The situation is just like on earth except you are not an inertial observer because you do not feel weightless. The observer inside the rocket would feel a force pushing up on the feet. Same on earth. You are accelerating in order to remain stationary. However you can not see yourself accelerating. In Newton’s rule the force of Gravity would be pushing you down and the ground pushing you up. However in special relativity gravity does not exist so it’s just the force of the ground pushing up on you. Just like the rocket accelerating. You look like you are not accelerating up but only in your frame of reference. To measure your speed of acceleration you must get an inertial observer to measure your acceleration speed. Like the man falling off the roof. Let’s say you are in the building and the man falls off the roof. To him you would appear accelerating upwards. So you have to accelerate just to stand still. Why all objects fall at the same rate is a mystery to Newtonian Physics but it is not a mystery to Special relativity because the objects are not accelerating just the floor accelerating into it.

So I hope you understand now, I think you know what I'm getting at. Might of misunderstood your question.

Answer:

Explanation:

there is no acceleration, it's velocity is always 6m/s

so your answer is 0m/s

Answer:

I believe it would be C ? my apologies if I'm wrong.

The distance traveled by the rocket after the given time period is 480 m.

The given parameters;

The distance traveled by the rocket after the given time period is calculated from the second kinematic equation of as shown below;

s = ut + ¹/₂at²

s = (10 x 12) + (0.5 x 5 x 12²)

s = 120 + 360

s = 480 m

Thus, the distance traveled by the rocket after the given time period is 480 m.

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Answer:

Explanation:

The momentum of an object can be found by using the formula

momentum = mass × velocity

From the question

mass = 1000 kg

velocity = 5 m/s

We have

momentum = 1000 × 5 = 5000

We have the final answer as

Hope this helps you

Answer:

nuclear fusion

Explanation:

converting hydrogen to helium.

The kinematics allows finding the answers for the positions of the body as a function of time and making its graph are:

Given parameters

To find

Kinematics studies the motion of bodies, gives relationships between the position, velocity and acceleration of bodies, let's use the relationship

          x = v₀ t + ½ a t²

Where x is the position, v or the initial velocity, at the acceleration and t is the time.

Let's substitute

           x = 5 t + ½ 2.5 t²

           x = 5 t + 1.25 t²

Let's calculate the position and write it in the table

t = 0 s       x = 0 m

t = 1 s        x = 5 1 + 1.25 1² = 6.25 m

t = 2 s       x = 5 2 + 1.25 2² = 15 m

t = 3s        x = 5 3 + 1.25 3² = 26.25 m

t = 4 s       x = 5 4 + 1.25 4² = 40 m

t = 5 s       x = 5 5 + 1.25 5² = 56.25 m

In the following table the time and positions of the body are given, these given are used for the attached graph

time (s)      position (m)

   0                  0

    1                  6.25

   2                 15

   3                 26.25

   4                 40

   5                 56.25

In conclusion, using kinematics we can find the answers for the positions of the body as a function of time and make its graph are:

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The application of a force on the box overcomes the friction and causes the box to accelerate

While the force is decreasing, the box will stabilize;

Reason:

Newton's third Law of Motion states that action and reaction are equal in magnitude and opposite in direction

When the box is pushed with a force, [tex]F_{you \, on \, box}[/tex], the reaction of the box of mass, m,  is as follows;

Where;

[tex]F_{friction}[/tex] = [tex]-F_{box}[/tex] for example

The negative sign is due to the direction of the friction force, or [tex]F_{box}[/tex] is opposite to the direction of the applied force

When the force is decreased to F₂ = [tex]F_{you \, on \, box}[/tex], such that we have;

[tex]F_{you \, on \, box}[/tex] = [tex]-F_{box \, on \, you}[/tex] , which is the condition for equilibrium, and the net

force is zero and according to Newton's first law of motion,  the box moves

at constant speed no acceleration

Therefore the box will reach equilibrium when;

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Answer:

When the force you are exerting on the box is equal to 0

Explanation:

Once again expert verifiers are sabotaging people here is the actual answer.

Answer:

The four types of thermodynamic process are isobaric, isochoric, isothermal and adiabatic.

Answer:

photosynthesis uses carbon dioxide

Explanation:

Consider the following statements:

1. Carbon dioxide, chlorophyll, and sunlight are all essential for photosynthesis.

2. Rate of photosynthesis is maximum in red light and minimum in green light.

3. Increase

concentration decreases the rate of photosynthesis.

Which of the statements given above are correct about photosynthesis?

Answer:

2.0 m/s

Explanation:

Remember that F = maF=maF, equals, m, a, where FFF is the net force, mmm is the mass of the object, and aaa is its acceleration. To solve this problem, we will need to first find the net force acting on the piano and then use F = maF=maF, equals, m, a to find the piano’s acceleration.

Hint #22 / 4

The net force is the sum of all of the forces on the piano. In this circumstance, Elvis's and Noah's forces are in the same direction, and the friction force is in the opposite direction. So, our net force equation would be:

​

=400 N+150 N−100 N

=450 N

Now, we can use F = maF=maF, equals, m, a and solve for the acceleration:

225 kg

450 N

=2.0

The acceleration of the piano is 2.0 m/s

The acceleration of the piano is 2m/s².

We know the formula for force is

F =ma

where f is force, m is mass and a is acceleration.

We need to calculate the total force used in moving the piano

F= Total force- Frictional force

F= 400N+150N-100N= 450N.

We have F=450N and m= 225kg

F=ma

450N= 225ˣ a

a= 450/225

a= 2m/s²

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Answer: 1 hour

Explanation: Focus on the units; 70 miles per hour means that each hour, you will travel 70 miles

or you can use the equation time = distance/speed. You have 70miles/ 70mph = 1hour

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Charge on one electron :

So, charge on ball having 97 electrons is equal to :

Answer:

the car slows down

Explanation:

Answer:

yes by 30

Explanation:

uhnhuh

Answer:

Because alkali metals are so reactive, they are found in nature only in combination with other elements. They often combine with group 17 elements, which are very “eager” to gain an electron.

Explanation:

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