a ball is thrown directly downward with an initial speed of 7.10 m/s, from a height of 30.8 m. after what time interval does it strike the ground?

The correct response is: the system is closed, and the net external force is nonzero.

The object-earth system is closed because there are no external forces acting on the system, as all the forces are internal, i.e., the gravitational force between the object and the earth. However, the net external force is not zero because the object is accelerating due to the force of gravity. The net external force is equal to the weight of the object, which is given by W = mg, where m is the mass of the object and g is the acceleration due to gravity. Therefore, the net external force is F_net = mg = 5 kg x 9.8 m/s^2 = 49 N.

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Answer:

as fuel is combusted,the rocket pushes the gas is backward and the gas is pushed the rocket forward

Explanation:

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The magnitude of compressive strength (cs) of concrete can be defined as the maximum amount of pressure concrete can bear before failing or fracturing.

Fracture of concrete would occur if the magnitude of tensile stress exceeds the tensile strength of the concrete. Concrete can bear compressive stress up to a specific limit beyond which it will fail and ultimately fracture. Therefore, to find out if the concrete fractures, we need to find the maximum compressive stress that the concrete can bear and compare it with the stress developed in the given case.Let's assume that the cross-sectional area of the concrete is A, and its length is L. In such a case, the change in length of the concrete is given by: ΔL = FL / AY, where F is the force applied, Y is Young's modulus, and A is the cross-sectional area. The magnitude of compressive stress developed in the concrete due to this force is given by:σ = F/AThe force required to produce a change of ΔL is given by:F = (A*Y*ΔL)/LTherefore, the magnitude of compressive stress developed in the concrete is given by:σ = (A*Y*ΔL)/(A*L)σ = YΔLSubstituting the values of Young's modulus and temperature in the formula, we get: Y = 7.00 × 10⁹ N/m²σ = YΔLσ = (7.00 × 10⁹ N/m²) × 0.0002σ = 1400 N/m²

The magnitude of compressive stress developed in the concrete is 1400 N/m², which is much smaller than the compressive strength of concrete, i.e., 2.00 × 10⁹ N/m². Hence, the concrete does not fracture.

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The energy required to raise the temperature of the air in a room by 5.0°C is 336 kJ

U =  \(c_{p}\) m ΔT

U = Energy

\(c_{p}\) = Specific heat

m = Mass

ΔT = Change in temperature

ρ = Density

V = Volume

ρ = 1000 g / m³ (Dry air )

\(c_{p}\) = 1 J / g K

ΔT = 5 °C

V = 4 * 4 * 3

V = 48 m³

m = ρ V

m = 1000 * 48

m = 48000 g

U = 1 * 48000 * 7

U = 336000 J

U = 336 kJ

Therefore, the energy required to raise the temperature of the air in a room by 5.0°C is 336 kJ

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Answer:

See below

Explanation:

Assuming no resistance

DISTANCE =  1/2 a t^2

443 = 1/2 (9.81)t^2      Shows t = 9.5 seconds

Answer:

Potential energy does not have an absolute measurement. It is always relative to some reference point. Gravitational potential always increases when you go up and decreases when you go down. But the choice of a zero point is arbitrary.

If you’re dropping objects onto the ground, then choosing the ground as a zero point makes the calculations easier. But you could just as easily make the zero point the top of Mt. Everest, and all the answers would turn out the same. Up still means more energy and down means less, but now the PE of an object at sea level would have a negative sign, but not as negative as an object ten meters above sea level.

So everything would still work fine.

In fact, planetary astronomers take this idea to extremes. Instead of the top of Mt. Everest, they set the zero point for potential energy as infinitely high—so far “up” that gravity is so weak that going “up” another kilometer doesn’t gain you any energy. Then the value for potential energy everywhere else in the universe anywhere near a planet has a negative sign, but just as before, all the answers in relative terms turn out fine.

Explanation:

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The maximum height the ball will rise if Jean throws it straight upward is 0 meters above the release point.

To find the maximum height the ball will rise if Jean throws it straight upward, we can use the concept of projectile motion. The key idea is that the vertical component of the initial velocity is zero at the highest point of the trajectory.
Given that the maximum horizontal distance is 58.2 m, we can assume that the initial speed (also known as the magnitude of the initial velocity) is constant for all launch angles.  

Let's denote the maximum height as "h" (measured in meters above the release point). At the highest point of the trajectory, the vertical velocity component will be zero.
Using the equation for the vertical displacement in projectile motion, we have:

Vertical displacement = (Initial vertical velocity * time) + (0.5 * acceleration due to gravity * time^2)

Since the ball is thrown straight upward, the initial vertical velocity is positive (upward). The acceleration due to gravity is negative (downward). Therefore, the equation becomes:
h = (0 * t) + (0.5 * (-9.8 m/s^2) * t^2)

Simplifying the equation, we have:
h = -4.9t^2

To find the time it takes for the ball to reach its highest point, we need to use the equation for the vertical component of the velocity:

Vertical velocity = Initial vertical velocity + (acceleration due to gravity * time)
Since the vertical velocity is zero at the highest point, we have:
0 = 0 + (-9.8 m/s^2) * t

Solving for t, we find:
t = 0

This means that at the highest point of the trajectory, the ball has been in the air for 0 seconds.
Substituting t = 0 into the equation for h, we find:
h = -4.9(0)^2
h = 0

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When Jean throws the ball straight upward, it will not rise to any height above the release point. It will only reach the same level as the release point. To determine the maximum height the ball will reach when thrown straight upward, we need to use the concept of projectile motion. When the ball is thrown straight upward, it experiences a vertical motion under the influence of gravity.

First, we need to find the initial vertical velocity of the ball. Since the ball is thrown straight upward, the initial vertical velocity is equal to zero.

Next, we need to find the time it takes for the ball to reach its maximum height. We can use the equation:

    t = (final velocity - initial velocity) / acceleration

The final velocity is zero, the initial velocity is zero, and the acceleration due to gravity is -9.8 m/s^2 (taking downward as negative). Therefore, the time taken to reach the maximum height is zero.

Now, we can use the equation for vertical displacement:

    Δy = (initial velocity * t) + (0.5 * acceleration * t^2)

Substituting the values, we get:

    Δy = (0 * 0) + (0.5 * -9.8 * 0^2)
=> Δy = 0

This means that the maximum height the ball will rise is 0 meters above the release point. The ball will reach the same level from where it was thrown, but not higher.

In conclusion, when Jean throws the ball straight upward, it will not rise to any height above the release point. It will only reach the same level as the release point.

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Let west be the negative direction, and east be positive. Then the total momentum of the system is conserved such that

(3.00 kg) (-2.00 m/s) + m (1.50 m/s) = 0

Solve for m :

m = (3.00 kg) (2.00 m/s) / (1.50 m/s) = 4.00 kg

The major characteristic an organic compound has which an inorganic

compound doesn't  have is the presence of carbon atoms in the molecule.

This helps us to differentiate the compounds into their respective divisions.

Inorganic compounds

Organic compounds

We can observe that inorganic compounds lack carbon atoms which makes

the answer valid.

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Answer:

B and E because yk thats the asnwer

The principles necessary to solve for the bullet's original velocity in the ballistic pendulum are Conservation of Momentum and Conservation of Energy.

Conservation of Momentum: This principle states that the total momentum of a system remains constant if no external forces act on it. In the ballistic pendulum, the momentum before the collision between the bullet and the pendulum is equal to the momentum after the collision.

Conservation of Energy: This principle states that the total energy of a system remains constant if no external forces do work on it. In the ballistic pendulum, the initial kinetic energy of the bullet is transferred to the pendulum as gravitational potential energy when the pendulum swings upward.

Therefore, the correct answer is:

Conservation of Momentum and Conservation of Energy.

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Answer:

repel , attract,l am sure with these two blanks only

Answer:

Magnetic fields

A magnet creates a magnetic field around it. You cannot see a magnetic field, but you can observe its effects. A force is exerted on a magnetic material brought into a magnetic field. The force is a non-contact force because the magnet and the material do not have to touch each other.

The shortest plane mirror in which you can see your entire image is typically half your body's height, assuming that the mirror is positioned vertically and you are standing in front of it.

When you stand in front of a plane mirror, the mirror reflects the light rays that hit it, creating a virtual image. The virtual image appears to be behind the mirror and is the same size as the object being reflected.

To see your entire image in the mirror, you need to position yourself in such a way that the top of your head and the bottom of your feet are both within the field of view of the mirror. Therefore, the height of the mirror should be at least equal to your body height.

However, if you position the mirror at an angle or tilt it, you may be able to see your entire image in a mirror that is shorter than half your body height. The angle and orientation of the mirror will affect the field of view and the visibility of your image.

It's important to note that this measurement assumes an average human body height and a mirror that is positioned vertically. Individual variations in height and the specific arrangement of the mirror can affect the minimum height of the mirror needed to see your entire image.

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The peak of solar radiation occurs in part of the electromagnetic spectrum i.e. Visible light. Hence, the correct option is (c).

The peak of solar radiation occurs in the visible light part of the electromagnetic spectrum. The Sun emits energy across a wide range of wavelengths, including radio waves, microwaves, visible light, and gamma rays. However, when we analyze the distribution of this energy, we find that the maximum amount of radiation is emitted in the visible light region.

Visible light consists of various colors, each corresponding to a specific wavelength. The Sun emits the most energy at wavelengths that correspond to the colors green and yellow, which is why we perceive sunlight as being predominantly yellowish. This peak in energy emission in the visible light range is essential for sustaining life on Earth, as it enables photosynthesis in plants and allows us to see.

While other parts of the electromagnetic spectrum, such as radio waves, microwaves, and gamma rays, are also emitted by the Sun, the peak of solar radiation occurs in the visible light range. This peak is significant for various biological processes and plays a crucial role in the functioning of our planet.

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Answer:

The radius will be "100.31 m". A further solving is given below.

Explanation:

The given values are:

Time,

T = 2 minutes

i.e.,

 = 120 seconds

Speed,

V = 5.25 m/s

As we know

⇒  \(T=\frac{2 \pi R}{V}\)

then,

⇒  \(R=\frac{TV}{2 \pi}\)

On substituting the given values, we get

⇒      \(=\frac{120\times 5.25}{2\times 3.14}\)

⇒      \(=\frac{630}{6.28}\)

⇒      \(=100.31 \ m\)

The speed of the man and the chair after the book is thrown is 0.2 m/s.

The given parameters:

The total mass of the man and the book is calculated as follows;

m₂ = 70 kg + 9.2 kg

m₂ = 79.2 kg

The speed of the man and the chair after the book is thrown is determined by applying the principle of conservation of linear momentum;

\(m_1 u_1 = m_2u_2\\\\u_2 = \frac{m_1u_1}{m_2} \\\\u_2 = \frac{2.1 \times 7.2}{79.2} \\\\u_2 = 0.2 \ m/s\)

Thus, the speed of the man and the chair after the book is thrown is 0.2 m/s.

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The total displacement of the vectors is 2 km south.

Distance is the total path that an object in motion has traveled. Displacement is a verb that denotes the movement or displacement of an object.

Here, the vector moves 4 km towards the south, then moves 2 km north. The vector again moves 5 km south and moves 5 km north. Draw the diagram, mentioning the  4 km south movement by the black arrow, the 2 km north movement by the blue arrow, the 5 km south movement by the orange arrow, and the 5km north movement by the green arrow.

Also, mark the starting and ending points. These points give the displacement of the diagram. From the diagram, we can tell, the displacement is 2 km south of the starting point.

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(a) Using the information in table 26.2, we can find the resistivity of aluminum at this temperature. From the table, we find that the resistivity of aluminum at \(50.08°C is 2.83 x 10^-8 Ωm.\)

(b) The current density J in the wire is given by:

\(J = σE\)

where σ is the conductivity of aluminum and E is the electric field. Since σ = 1/ρ, where ρ is the resistivity, we have:

J = (1/ρ)E

Plugging in the values, we get:

\(J = (1/2.83 x 10^-8 Ωm)(0.200 V/m) = 7.06 x 10^6 A/m^2\)

(c) The total current I in the wire is given by:

I = JA

where A is the cross-sectional area of the wire. The cross-sectional area of the wire can be calculated using the formula:

\(A = πr^2\)

where r is the radius of the wire, which is half of the diameter. So, we have:

\(A = π(0.100/2 x 10^-3 m)^2 = 7.85 x 10^-8 m^2\)

Plugging in the values, we get:

\(I = (7.06 x 10^6 A/m^2)(7.85 x 10^-8 m^2) = 0.554 A\)

(d) The drift speed v of the conduction electrons can be calculated using the formula:

\(v = (J/ne)(1/A)\)

where n is the number of free electrons per unit volume of the wire, and e is the charge of an electron. Since there is one free electron per atom and the atomic mass of aluminum is 26.98 g/mol, we can calculate the number density of aluminum atoms using the formula:

\(ρ = (N/V)m\)

where N is Avogadro's number, V is the molar volume of aluminum, and m is the atomic mass of aluminum. Plugging in the values, we get:

\(ρ = (6.022 x 10^23/mol)(10.0 cm^3/mol)(26.98 g/mol)/(1000 g/kg) = 2.699 x 10^22 atoms/m^3\)

Since each atom has one free electron, the number density of free electrons is also 2.699 x 10^22 electrons/m^3. Plugging in the values, we get:

\(v = (J/ne)(1/A) = (7.06 x 10^6 A/m^2)/(2.699 x 10^22/m^3)(1/7.85 x 10^-8 m^2) = 0.054 m/s\)

(e) The potential difference V required to produce the stated electric field along a length L of the wire is given by:

V = EL

Plugging in the values, we get:

\(V = (0.200 V/m)(2.00 m) = 0.400 V\)

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Answer:

Second choice

Explanation:

I suppose ME is the same as POTENTIAL energy

ME = mgh =  70 * 10 * 12 = 8400j

  Half way down,   4200 j is converted to Kinetic Energy

       1/2 m v^2 = 4200

       1/2 (70)  v^2 = 4200       v = 10.95 m/s

  Just before impact ALL of the 8400 j is now KE
      1/2 (70)v^2 = 8400          v = 15.49 m/s

The pressure exerted is 4 × 10⁷ N/m²

Pressure is the force carried out perpendicular to the surface of an item in step with the unit vicinity over which that force is sent. Gauge pressure is the pressure relative to the ambient strain. numerous units are used for the explicit strain.

Strain is a pressure carried out perpendicular to the surface of an item in keeping with unit location. Mathematically it is P = F/A, in which P is strain, F is force, and A is area. strain is a scalar amount, one that most effectively has value and no directional vector characteristics.

Calculation:-

Given,

area = 0.25 mm2

        = 2.5 × 10⁻⁷ m²

Force = 10 N

Pressure = force/area

              = 10 / 2.5 × 10⁻⁷

              = 4 × 10⁷ N/m²

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(a) The effort required to push the block up the slope is 3600 N.

(b) the ideal mechanical advantage of the slope is 2.92

(c) The efficiency of the slope is 68.5%.

a) To calculate the effort required to push the block up the slope, we can use the formula:

Effort = Load / AMA

where;

Load = 7200 N

AMA = 2

Effort = 7200 N / 2

Effort = 3600 N

b) The ideal mechanical advantage (IMA) of an inclined plane is given by the formula:

IMA = Length of slope / Height of slope

Length of slope = 100 m

Angle of slope = 20°

We can use trigonometry to find the height of the slope:

Height of slope = Length of slope x sin(angle of slope)

Height of slope = 100 m x sin(20°)

Height of slope = 34.2 m (rounded to one decimal place)

Therefore, the ideal mechanical advantage of the slope is:

IMA = 100 m / 34.2 m

IMA = 2.92 (rounded to two decimal places)

c) The efficiency of the slope is given by the formula:

Efficiency = AMA / IMA x 100%

AMA = 2

IMA = 2.92

Efficiency = 2 / 2.92 x 100%

Efficiency = 68.5% (rounded to one decimal place)

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B) Globular clusters. Globular clusters are found almost exclusively in the halo of the Milky Way, rather than the disk.

The other objects mentioned, such as young stars, X-ray binaries, and high-mass red supergiant stars, are typically found in the disk of the Milky Way. Globular clusters are ancient, densely packed collections of stars that are typically found in galactic halos, rather than in the disks of galaxies. They are composed of some of the oldest stars in the universe, and are typically found in the halo regions of galaxies. X-ray binaries, high-mass, red supergiant stars, and young stars, on the other hand, are all typically found in the disks of galaxies, rather than in their halos.

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Answer: Earthquakes and Volcanic eruptions

Explanation:

You did not attach a picture however, this should be the correct answer.

Mid-oceanic ridge plate  boundaries such as the Mid-Atlantic Ridge form as a result of plate separating at the boundary. This leads to earthquakes due to the forces of tension acting on the plates.

When this happens, the mantle is exposed and therefore there will be volcanic eruptions as the lava comes to the surface as magma. When this magma cools it creates new seafloors and underwater mountains.

To calculate the work needed for a 68-kg runner to accelerate from rest to 7.5 m/s, we can use the equation: work = 1/2 * mass * velocity^2 Plugging in the values we have: work = 1/2 * 68 kg * (7.5 m/s)^2 work = 1906.25 joules Therefore, the amount of work needed for the runner to accelerate from rest to 7.5 m/s is 1906.25 joules.

To calculate the work needed for a 68-kg runner to accelerate from rest to 7.5 m/s, we'll use the work-energy principle, which states that work equals the change in kinetic energy. The formula for kinetic energy is KE = 0.5 * m * v^2, where m is mass and v is velocity.
Initial kinetic energy (rest): KE_initial = 0.5 * 68 kg * 0 m/s^2 = 0 J (joules)
Final kinetic energy: KE_final = 0.5 * 68 kg * (7.5 m/s)^2 = 1912.5 J
Now, we find the work done by calculating the change in kinetic energy:
Work = KE_final - KE_initial = 1912.5 J - 0 J = 1912.5 J
So, the work needed for a 68-kg runner to accelerate from rest to 7.5 m/s is 1912.5 Joules.

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When very dense material is heated, it produces a continuous spectrum. A continuous spectrum is an electromagnetic radiation that displays a continuous range of wavelengths or colors.

The spectrum has no gaps or breaks and is seen as a smooth, unbroken band of colors that blend into each other.A continuous spectrum is created by solids, liquids, and dense gases when heated. The molecules in these materials begin to move around more quickly when they absorb thermal energy.

As a result of this motion, the electrons in the atoms within the material are excited to higher energy levels.This means that the electrons move from lower energy levels, which are closer to the atomic nucleus, to higher energy levels, which are further away from the nucleus. When the electrons transition back to their lower energy states, they release energy in the form of electromagnetic radiation.

The radiation that is released includes a continuous range of wavelengths, which produce a continuous spectrum.Continuous spectra are important in astronomy because they help scientists learn about the temperatures of the objects producing the radiation. By analyzing the spectrum, they can determine the temperature of the object.

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Answer:

D

Explanation:

speed = frequency x wavelength

speed of light in vacuum is 3.0 x 10^8

wavelength = 5.32 x10 ^-7

3.0 x 10 ^ 8 = 5.32 x 10^-7 x frequency

frequency = 5.63909 x 10^14

round it off = 5.64 x 10^14 Hz

thus the answer is D

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