3. A skater moves across the ice a distance of 12 m before a constant frictional force of 15 N cause him to stop. His initial speed is 2.2 m/s . Calculate the skater's mass.

Answer:

me...:(

Explanation:

Answer:

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Answer:

to be honest i dont know

Explanation:

^^

Answer:

The new force becomes (1/9)th of the original force.

Explanation:

The gravitational force between two masses is given by :

[tex]F=G\dfrac{m_1m_2}{r^2}[/tex]

Where

r is the distance between masses,

If the new distance is, r' = 3r

The new force is given by :

[tex]F'=G\dfrac{m_1m_2}{r'^2}\\\\F'=G\dfrac{m_1m_2}{(3r)^2}\\\\F'=\dfrac{1}{9}\times G\dfrac{m_1m_2}{r^2}\\\\F'=\dfrac{F}{9}[/tex]

So, the new force becomes (1/9)th of the original force.

Answer: 321 J

Explanation:

Given

Mass of the box [tex]m=3\ kg[/tex]

Force applied is [tex]F=25\ N[/tex]

Displacement of the box is [tex]s=15\ m[/tex]

Velocity acquired by the box is [tex]v=6\ m/s[/tex]

acceleration associated with it is [tex]a=\dfrac{F}{m}[/tex]

[tex]\Rightarrow a=\dfrac{25}{3}\ m/s^2[/tex]

Work done by force is [tex]W=F\cdot s[/tex]

[tex]W=25\times 15\\W=375\ J[/tex]

change in kinetic energy is [tex]\Delta K[/tex]

[tex]\Rightarrow \Delta K=\dfrac{1}{2}m(v^2-0)\\\\\Rightarrow \Delta K=\dfrac{1}{2}\times 3\times 6^2\\\\\Rightarrow \Delta K=\dfrac{1}{2}\times 3\times 36\\\\\Rightarrow \Delta K=54\ J[/tex]

According to work-energy theorem, work done by all the forces is equal to the change in the kinetic energy

[tex]\Rightarrow W+W_f=\Delta K\quad [W_f=\text{Work done by friction}]\\\\\Rightarrow 375+W_f=54\\\Rightarrow W_f=-321\ J[/tex]

Therefore, the magnitude of work done by friction is [tex]321\ J[/tex]

Answer: The frequency of a pendulum is [tex]0.2 s^{-1}[/tex].

Explanation:

Time period is defined as the time required to produce complete wave.

As we know that the frequency and time are inversely proportional to each other.

That means,

[tex]\nu =\frac{1}{T}[/tex]

Where,

[tex]\nu[/tex] is frequency of pendulum

T is time period

Given:

Time period = 5 seconds

Now putting all the given values in the above formula, we get the frequency of the pendulum.

[tex]\nu =\frac{1}{T}\\\\\nu =\frac{1}{5s}\\\\\nu =0.2s^{-1}[/tex]

Therefore, the frequency of a pendulum is [tex]0.2 s^{-1}[/tex].

Answer:

The answer is Newton's third law of motion states that every action has an equal and opposite reaction. This means that force always act in pairs

The pair of forces described by Newton third law must be in opposite direction.

Every action have equal and opposite reaction. for example when we fire bullet from a gun, the gun will recoil back and bullet moves forward. In case of rocket, rocket is fired, thrust is reaction of force applied by the gas on the floor.

The motion of lift from an airfoil in which the air is diverted downward by the airfoil's action and the wing is pushed upward in response.

When a spinning ball moves, the air is deflected to one side, and the ball responds by travelling in the other direction.

A jet engine's motion generates thrust, and hot exhaust gases rush out the back of the engine, producing thrust in the opposite direction.

To know more about motion :

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Answer:

Option D

Explanation:

From the question we are told that:

The attractive magnetic force per unit length as

 [tex]f = F/L[/tex]

Separation Distance [tex]x=2d[/tex]

Generally the equation for  Magnetic force between two current carrying wire is mathematically given by

[tex]\frac{F}{\triangle l}=\frac{\mu_0I_1I_2}{\mu \pi x}[/tex]

[tex]\frac{F}{\triangle l }=\frac{I_1I_2}{ x}[/tex]

Where

[tex]x=2r[/tex]

And

[tex]I_1=I_2=>2I[/tex]

Then

[tex]\frac{F}{\triangle l}=>\frac{2*2}{2}*f[/tex]

[tex]\frac{F}{\triangle l}=>2f[/tex]

Therefore s the force per unit length between the wires if their separation is 2d

[tex]\frac{F}{\triangle l}=>2f[/tex]

Option D

Answer:

200 N

Explanation:

Applying,

The force a golie must exert on the ball is,

F = ma...................... Equation 1

Where m = mass of the ball, a = acceleration of the ball.

But,

a = Δv/t............... Equation 2

Where Δv = change in velocity, t = time.

Substitute equation 2 into equation 1

F = m(Δv/t)............... Equation 3

From the question,

Given: m = 0.8 g, t = 0.1 s, Δv = 25 m/s

Substitute these values into equation 3

F = 0.8×25/0.1

F = 200 N

Answer:

[tex](b)\ t_1 - t_0[/tex]

[tex](d)\ t_2 - t_1[/tex]

[tex](e)\ \frac{t_2 - t_0}{2}[/tex]

Explanation:

Given

See attachment for complete question

Required

How long to reach the ground from the maximum height

First, calculate the time of flight (T)

[tex]T =t_2 - t_0[/tex]

The time taken (t) from maximum height to the ground is:

[tex]t = \frac{1}{2}T[/tex]

So, we have:

[tex]t = \frac{t_2 - t_0}{2}[/tex]

Another representation is:

At ymax, the time is: t1

On the ground, the time is t2

The difference between these times is the time taken.

So;

[tex]t = t_2 - t_1[/tex]

Since air resistance is to be ignored, then

[tex]t_2 - t_1 = t_1 - t_0[/tex] --- i.e. time to reach the maximum height from the ground equals time to reach the ground from the maximum height

Answer:

B is excellent answer..............

The model of the brain that is shown here is the experimental model that is present in Option B, as it is used to study the brain's parts and its function, which is helpful for a better understanding of the brain.

There are various experimental models of the brain that have been developed to better understand its functions and mechanisms, such as Animal models, such as mice, rats, and primates, have been widely used to study the brain due to their similarity to the human brain in terms of structure and function. Computer models can simulate brain function and behavior at various levels of detail, from individual neurons to large-scale brain networks. These models are useful for testing hypotheses and predicting outcomes, as well as for designing new experiments.

Hence, the model of the brain that is shown here is the experimental model that is present in Option B.

Learn more about the experimental model of the brain here.

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Answer:

Power = 24.41Watts

Explanation:

Find the diagram attached

Power output  = Force * distance/Time

Given

Force = 120lb

Distance = 9inches

Time = 5sec

Since

1lb = 4.4482216153 N

120lb  = 120 * 4.4482216153

120lb = 533.787N

9in to meters

9in = 0.0254*9

9in = 0.2286N

Power = 533.787*0.2286/5

Power = 24.41Watts

You decide to play fetch with your dog, who is sitting nextto you, so you throw a ball down a narrow hallway. The ballcomes to a stop 3.9 m down the hallway. The dog, startingfrom rest, runs after the ball with a constant acceleration of0.70m/s2until she reaches the ball. She grabs the ball whilestill running down the hallway uniformly accelerating(slowingdown) for 4.7 more seconds until she comes to a stop. What isthe total distance the dog travels to grab the ball and come toa final stop, starting from rest

Answer:

the work done by the motor is 1,044 J.

Explanation:

Given;

the output power of the motor, P = 0.7 hp

duration of the work, t = 2 s

The relationship between horse-power and watt is given as;

1 hp = 745.7 W

0.7 hp = ?

0.7 hp = 522 W = 522 J/s

The work done by the motor is calculated as;

W = Power x time

W = 522 J/s  x  2 s

W = 1,044 J

Therefore, the work done by the motor is 1,044 J.

Explanation:

a.)

We find the relative speed

u = vb + vc

b.)

chuck and the cart are at a rest position

mcartvc = mballvb

from part a above,

vc = u - vb

mcartu = vb(mcart + mball)

make vb the  subject of the equation

[tex]vb=\frac{mcartu}{mcart +mball}[/tex]

c.)

from anser a,

vb = u - vc

then mcart vc = mball(u-vc)

[tex]vc= \frac{Mballu}{Mcart+Mball}[/tex]

d.

Mballvb = (Mcart + Mball)vj

we make vj the subject to get her relative speed

[tex]vj=\frac{MballVb}{Mcart+Mball}[/tex]

e.

given the solution in part d above,

we have

[tex]vj=\frac{MballVb}{Mcart+Mball}[/tex]

remember,

vb = u - vc

such that

[tex]Vj = \frac{Mball(u-v)}{Mball +Mcart}[/tex]

thank you!

Complete question:

How many x-ray photons per second are created by an x-ray tube that produces a flux of x rays having a power of 1.00 W. Assume the average energy per photon in 78.0 keV.

Answer:

The number of x-ray photons per second created by the x-ray tube is 8.01 x 10¹³ photons/sec

Explanation:

Given;

power of the flux produced, P = 1 W = 1 J/s

energy per photon, E = 78 keV

Convert the energy per photon to J

E = 78 x 10³ x 1.6 x 10⁻¹⁹ = 1.248 x 10⁻¹⁴ J / photon

let the number of photons = n

n(1.248 x 10⁻¹⁴ J / photon) = 1 J/s

[tex]n = \frac{1 \ J/s}{1.248 \times 10^{-14}\ J/photon } = 8.01 \times 10^{13} \ photons/s[/tex]

Therefore, the number of x-ray photons per second created by the x-ray tube is 8.01 x 10¹³ photons/sec

Answer:

a. True

Explanation:

Conduction involves the transfer of electric charge or thermal energy due to the movement of particles. When the conduction relates to electric charge, it is known as electrical conduction while when it relates to thermal energy, it is known as heat conduction.

A conductor can be defined as any material or physical object that allows the conduction (transfer) of electric charge or thermal energy. Some examples of conductors are metal, steel, aluminum, copper, frying pan, pot, metallic spoon, etc.

During heat conduction, thermal energy is usually transferred from fast moving particles to slow moving particles during the collision of these particles.

Furthermore, any charge that is added to a conductor would quickly spread over the surface of the conducting object due to the fact that it allows the movement of subatomic particles.

Answer: True

Explanation: Aced Test

Momentum = (mass) x (speed)

If you work the problem in the same units as the given data, then you get the momentum in units of kilogram-meters per second, and your horse has 1,440 of them.

Answer:

A

Explanation:

1440 kg*m/s

Answer: [tex]56.4\ m/s^2, 201.42\ m/s^2[/tex]

Explanation:

Given

Rocket attain a velocity of [tex]v=282\ m/s[/tex] in a time period of [tex]t=5\ s[/tex]

It was brought jarringly back to rest in only [tex]t'=1.4\ s[/tex]

Acceleration is the change in velocity of the object over a period of time

(a) Acceleration in his direction of motion

[tex]\Rightarrow a=\dfrac{v-0}{t}\\\\\Rightarrow a=\dfrac{282}{5}\\\\\Rightarrow a=56.4\ m/s^2[/tex]

(b) acceleration opposite to his direction of motion i.e. deceleration is

[tex]\Rightarrow a_d=\dfrac{0-v}{t'}\\\\\Rightarrow a_d=\dfrac{-282}{1.4}\\\\\Rightarrow a_d=-201.42 \ m/s^2\\\Rightarrow a_d=201.42\ \text{decelration}[/tex]

Answer:

The correct answer is "[tex]0.5\times 10^{-6} \ m[/tex]".

Explanation:

Given:

[tex]\frac{\lambda D}{d} =2.8\times 10^{-3}[/tex]

[tex]d = 0.5\times 10^{-3}[/tex]

[tex]D = 2.80[/tex]

Now,

The wavelength will be:

⇒ [tex]\lambda = 2.8\times 10^{-3}\times \frac{d}{D}[/tex]

By putting the values, we get

⇒    [tex]=\frac{2.8\times 10^{-3}\times 0.5\times 10^{-3}}{2.8}[/tex]

⇒    [tex]=\frac{1.4\times 10^{-6}}{2.8}[/tex]

⇒    [tex]=0.5\times 10^{-6} \ m[/tex]  

Impact printers involve mechanical components for conducting printing. It is a type of printer that works by direct contact of an ink ribbon with paper.

In Non-Impact printers, no mechanical moving component is used.

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Answer:

2

Explanation:

Force is mass into acceleration

and pressure is force applied per unit area.

Answer:

transparent

Explanation:

Answer:

Many people are not clear about the difference between our Solar System, our Milky Way Galaxy, and the Universe.

Let’s look at the basics.

Our Solar System consists of our star, the Sun, and its orbiting planets (including Earth), along with numerous moons, asteroids, comet material, rocks, and dust. Our Sun is just one star among the hundreds of billions of stars in our Milky Way Galaxy. If we shrink the Sun down to smaller than a grain of sand, we can imagine our Solar System to be small enough to fit onto the palm of your hand.  Pluto would orbit about an inch from the middle of your palm.

Artist diagram of Milky Way galaxy

On that scale with our Solar System in your hand, the Milky Way Galaxy, with its 200 – 400 billion stars, would span North America (see the illustration on the right). Galaxies come in many sizes. The Milky Way is big, but some galaxies, like our Andromeda Galaxy neighbor, are much larger.

The universe is all of the galaxies – billions of them! NASA’s telescopes allow us to study galaxies beyond our own in exquisite detail, and to explore the most distant reaches of the observable universe. The Hubble Space Telescope made one of the deepest images of the universe, called the Hubble Extreme Deep Field (image at the top of this article). Soon the James Webb Space Telescope will be exploring galaxies forming at the very beginning of the universe.

You are one of the billions of people on our Earth.  Our Earth orbits the Sun in our Solar System.  Our Sun is one star among the billions in the Milky Way Galaxy.  Our Milky Way Galaxy is one among the billions of galaxies in our Universe.  You are unique in the Universe!

You can observe objects in our solar system and even see other galaxies at a star party near you-and rest assured that everything you are seeing  is a part of the same universe as you!

Explanation:

A solar system is the system of celestial bodies built around a central star, the Sun. All of the system bodies, be they dwarf planets, small bodies and large planets, are held in a gravitational bond around the central star. Our solar system has eight large planets:

Four inner planets which are terrestrial, made entirely of rock and metal: Mars, Mercury, Earth and Venus;

Four outer planets which are gas and ice giants: Jupiter and Saturn (composed entirely of helium and hydrogen), Uranus and Neptune (composed of ices such as water, ammonia and methane).

The solar system also contains asteroid belts and the natural satellites of some of the planets. The trans-Neptunian region has the Kuiper belt, home to several dwarf planets, Pluto among them. Our solar system is located on the Orion Arm and is part of the Milky Way Galaxy. It was formed 4.6 billion years ago.

A galaxy is made out of billions of stars and their solar systems, held together by gravity, with a super- massive black hole at the center. Our Solar System is called the Milky Way; it is a spiral galaxy and the black hole in the center is called Sagittarius A*. Apart from the spiral shape, galaxies can also be elliptical or irregular in form. Galaxies gather in groups, clusters and super-clusters and there are billions of Galaxies in the Universe.

Some of these other galaxies are visible to the naked eye on a dark night and from places away from artificial light sources. The Andromeda Galaxy is the most recorded one throughout time and all over the world, its existence having been noted since the 10th century by Persian astronomer Al-Sufi, and having been the object of debate among other great thinkers up to the moment when the technology caught up to the discourse.

Solar System vs Galaxy

So what is the difference between a solar system and a galaxy?

A solar system represents the group of planets gravitationally bound to the central star. A galaxy has billions of stars and their solar systems. This difference in size is not only visible in the number of stars it is made out of, but also by how long it takes to cross it. It takes one light year to cross our solar system, and 100,000 light years to cross the galaxy.

While the biggest thing inside a solar system is the central sun, the biggest thing inside a galaxy is a massive black hole. The planets in a solar system orbit the sun, which is at the center, and the Sun, in turn, orbits the center of the Milky Way.

Comparison Chart

Solar system Galaxy

A group of planets orbiting the central sun A group of planetary systems whose central Suns are orbiting the center of the Galaxy

Gravitationally bound Gravitationally bound

Can be crossed in 1 light year Can be crossed in 100,000 light years

Most of the system mass is taken up by the central sun It hosts a super massive black hole, Sagittarius A*

More solar systems make up galaxies More galaxies make up the Universe

Answer:

The cost of energy is $ 0.34.

Explanation:

The energy is the capacity to do work.

The energy is a scalar quantity and its SI unit is Joule.

The commercial unit of energy is kWh.

Cost of 1 kWh energy = $ 0.17

energy loss by standard window is 2 kWh .

So, the cost of lost of energy is

Cost = $ 0.17 x 2 = $ 0.34

Answer:

kinetic energy of the train = 2,910.6 x 10⁷ joule

Explanation:

Given:

Mass of train = 3.3 x 10⁷ kg

Speed of train = 42 m/s

Find:

kinetic energy of the train

Computation:

kinetic energy = (1/2)(m)(v²)

kinetic energy of the train = (1/2)(3.3 x 10⁷)(42²)

kinetic energy of the train = (1/2)(3.3 x 10⁷)(1,764)

kinetic energy of the train = (3.3 x 10⁷)(882)

kinetic energy of the train = 2,910.6 x 10⁷ joule

Answer: The initial kinetic energy of the train is [tex]2910.6 \times 10^{7} J[/tex].

Explanation:

Given: Mass = [tex]3.3 \times 10^{7} kg[/tex]

Speed = 42 m/s

Kinetic energy is the energy acquired by an object due to its motion.

Formula to calculate kinetic energy is as follows.

[tex]K.E = \frac{1}{2}mv^{2}[/tex]

where,

m = mass of object

v = speed of object

Substitute the values into above formula as follows.

[tex]K.E = \frac{1}{2}mv^{2}\\= \frac{1}{2} \times 3.3 \times 10^{7} kg \times (42 m/s)^{2}\\= 2910.6 \times 10^{7} kg m^{2}/s^{2} (1 J = 1 kg m^{2}/s^{2})\\= 2910.6 \times 10^{7} J[/tex]

Thus, we can conclude that the initial kinetic energy of the train is [tex]2910.6 \times 10^{7} J[/tex].

Answer:

5.619×10⁶ N

Explanation:

Applying,

F = kqq'/r²................... Equation 1

Where F = electrostatic force between the charges, k = coulomb's constant, q = first charge, q' = second charge, r = distance btween the charges

From the questiion,

Given: q = 2.5 C, q' = 2.5 C, r = 100 m

Constant: 8.99×10⁹ Nm²/C²

Substitute these values into equation 1

F = (2.5×2.5×8.99×10⁹)/100²

F = 56.19×10⁵

F = 5.619×10⁶ N