Riding your skateboard, it takes 12 seconds to speed up from 2 m/s to 8 m/s. Find the acceleration.

It would take 1.556 seconds for the barrier to crumple and safely slow down the person with a force of 1180 N.

To calculate the time required to crumple the barrier and safely slow down the person, we can use the concept of impulse.

The impulse, denoted by J, is defined as the product of force and time, and it represents the change in momentum of an object. In this case, the impulse required to safely slow down the person can be calculated using the maximum force and the person's initial momentum.

The momentum of a person is given by the product of their mass and velocity:

Momentum = mass × velocity

Given that the person's mass is 68 kg and their velocity is 27 m/s, the initial momentum is:

Initial momentum = 68 kg × 27 m/s

To safely slow down the person, the impulse provided by the barrier should be equal to the change in momentum.

Therefore, we have:

Impulse provided by barrier = Final momentum - Initial momentum

Since the person is brought to rest, the final momentum is zero. Thus, we have:

Impulse provided by barrier = -Initial momentum

Now we can express the impulse in terms of force and time:

Impulse provided by barrier = Force × Time

Plugging in the known values, we can solve for time:

-Initial momentum = Force × Time

68 kg × 27 m/s = 1180 N × Time

Simplifying the equation, we find:

Time = (68 kg × 27 m/s) / 1180 N

Evaluating the expression:

Time = 1836 kg·m/s / 1180 N

Finally, converting kg·m/s to seconds, we get:

Time ≈ 1.5559 seconds

Therefore, it would take approximately 1.556 seconds for the barrier to crumple and safely slow down the person with a force of 1180 N.

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The bright star found near RA= 0h 45m and DEC= -18° is Canopus. It is located in the southern hemisphere in the constellation of Carina.

Canopus is the second-brightest star in the sky, after Sirius. It is one of the brightest stars in the sky and can be seen from all over the world, including the southern hemisphere, where it is most visible.

Canopus is a white supergiant star that is roughly 71 times bigger than the Sun and 13,600 times more luminous than it. It is around 310 light-years away from Earth and has a surface temperature of around 7400 K (7673°C).

The temperature of Canopus is 7400 K which is equal to 7673°C. The temperature of Canopus is around 7400 K (7673°C) which is considerably higher than the temperature of the Sun. Canopus is a white supergiant star, which is a very luminous and massive type of star that burns very hot and bright.

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Answer:

no

Explanation:

Explanation:

Wave front, imaginary surface representing corresponding points of a wave that vibrate in unison. ... Wave fronts for longitudinal and transverse waves may be surfaces of any configuration depending on the source, the medium, and the obstructions encountered.

Answer:

7A

Explanation:

Current I = potential difference V ÷ Resistance R

I = V/R ........1

The overall resistance of parallel resistors is;

1/Rt = 1/R1 + 1/R2 ........2

Given;

V = 10V

R1 = 2 ohms

R2 = 5 ohms

Substituting the values into equation 2, to calculate the overall resistance;

1/Rt = 1/2 + 1/5

1/Rt = 7/10

Rt = 10/7 ohms

From equation 1, we can solve for the total current;

I = V/Rt = 10/(10/7)

I = 7A

The total current I flowing through a system is 7A

Medium Earth Orbit Satellites are the most expensive to build and launch but have the longest orbital life.

A medium Earth orbit Satellites(MEO) is an Earth-centered orbit that is between 1,243 and 22,236 miles (1,243 km) above sea level and is higher than a low Earth orbit (LEO) but lower than a high earth orbit (HEO).

In contrast to the boundary between MEO and LEO, which is an arbitrary altitude determined by recognized practice, the boundary between MEO and HEO is the specific altitude of a geosynchronous orbit, in which a satellite circles the Earth once every 24 hours, or one full revolution of the Earth. All MEO satellites have orbital periods that are fewer than 24 hours, with the shortest periods (for circular orbits at the lowest MEO altitude) being under 2 hours. Solar radiation pressure, which affects satellites on MEO orbits,

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Answer:

The turning effect of a force is known as the moment. It is the product of the force multiplied by the perpendicular distance from the line of action of the force to the pivot or point where the object will turn. When undoing a nut fastened to a screw by hand one realises that the amount of force required is a lot greater than when undoing the same nut using a spanner.

Explanation:

Daniela had a 5-meter head start and Leonard caught up to her at 25 meters best describes the runners. Option A is correct.

Distance is a numerical representation of the distance between two objects or locations.

The distance can refer to a physical length or an estimate based on other factors in physics or common use. |AB| is a symbol for the distance between two points A and B.

The graph shows that Daniela had a 5-meter head start and Leonard caught up to her at 25 meters

Hence option A is correct.

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Answer:

Daniela had a 5 meter head start, and Leonard caught up to her at 25 meters.

Explanation: took the unit test

Answer:

Horizontal component = 60.05 m/s

vertical component = 22.96 m/s

Explanation:

cosine(angle) = adjacent / hypotenuse or  horizontal / angled velocity

angled velocity * cosine (angle) = horizontal velocity

65 m/s * cosine(22.5) = 60.05 m/s

sine(angle) = adjacent/ hypotenuse or vertical/ angled velocity

angled velocity * sine (angle) = vertical velocity

65m/s sine(22.5) = 22.96 m/s

Answer:

Micro Waves

Explanation:

Microwaves in particular are used by cell phone calls for wireless communication. A portion of radio waves with higher frequency makes up these microwaves. The cellphone's antenna transforms speech data into microwaves during a call, and these microwaves travel through the atmosphere to the closest cell tower. The tower takes in and sends the microwaves to the mobile device of the intended receiver. The gadget receives the microwaves and transforms them back into electrical signals so the recipient can hear the voice data. By employing the strength of microwaves, this technology provides wireless communication and permits mobile users to communicate from anywhere inside the cellular network's service area.

The type of waves that are used to make and receive cellphone calls are radio waves.

Radio waves are a type of electromagnetic radiation that has a long wavelength and low frequency. These waves are used for communication purposes because they are able to travel long distances without losing their signal strength. When a person makes a call on their cellphone, their voice is converted into an electrical signal that is sent through the cellphone's antenna as a radio wave. This radio wave is then picked up by the nearest cell tower, which receives the signal and sends it through the network to the person on the other end of the call. The process is reversed when the other person responds, with their voice being converted into a radio wave that is sent back through the network to the caller's phone.

In summary, radio waves are the type of waves that are used to make and receive cellphone calls due to their ability to travel long distances without losing signal strength.

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Answer:

W = V Q          energy = work / charge * charge

Q = I t            charge = current * time

V = W / (I * t)

V = 3 * 10E8 J / (1.5 * 10E4 amps * 2 * 10E-4 sec)

V = 10^8 volts

The answer to the given question is option C: 40.4°F. Let's see the explanation below.How to find the temperature difference across a properly operating electric furnace?

]We know that the temperature difference across a properly operating electric furnace is given by:ΔT = (Q / (1.08 * CFM))where,Q is the rate of heat input in BTU/hr,1.08 is the factor to convert CFM to lb/min,and CFM is the rate of air flow in cubic feet per minute.So, here,ΔT = (Q / (1.08 * CFM))

Given,The rate of heat input = 10 kW = 34,120 BTU/hrThe rate of air flow = 900 CFMPlugging these values in the above equation, we get:ΔT = (34,120 / (1.08 × 900))ΔT = 40.4°FTherefore, the temperature difference across a properly operating electric furnace that is using a 10-kW electric heater and is moving 900 cfm of air is 40.4°F. Hence, the main answer is option C.

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The temperature difference across the electric furnace is approximately 30.2°F (option A).

To calculate the temperature difference across the electric furnace, we can use the formula:

Temperature difference (ΔT) = Heat (Q) / (Airflow rate * Specific heat capacity * Density)

First, let's convert the power of the electric heater from kilowatts (kW) to watts (W):

10 kW = 10,000 W

Next, we need to determine the specific heat capacity of air. Typically, it is around 0.24 BTU/lb°F.

Since the given airflow rate is in cubic feet per minute (cfm), we need to convert it to pounds per minute (lb/min) using the density of air. The density of air at standard conditions is approximately 0.075 lb/ft³.

Converting 900 cfm to lb/min:

900 cfm * 0.075 lb/ft³ = 67.5 lb/min

Now we can substitute the values into the formula:

ΔT = 10,000 W / (67.5 lb/min * 0.24 BTU/lb°F * 0.075 lb/ft³)

Simplifying the equation:

ΔT = 10,000 W / (67.5 * 0.24 * 0.075) (lb/min * BTU/lb°F * lb/ft³)

Calculating the result:

ΔT ≈ 30.2°F

Therefore, the temperature difference across the electric furnace is approximately 30.2°F, which corresponds to option A.

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we can equate the two quantities of heat to find c: m_water * c_water * ΔT = m_material * c * ΔT, c = (m_water * c_water * ΔT) / (m_material * ΔT)

the above expression yields c = 0.20 kcal/kg * C°.

The formula for calculating the specific heat (c) of a material is:

ΔQ = m * c * ΔT

c = ΔQ / (m * ΔT)

ΔT = 100°C - 40°C = 60°C

m_water = 100 gΔQ = m_water * c_water * ΔT = 100 g * 1.00 kcal/kg * ΔT

m_material = 50 g

ΔT = 40°C - 0°C = 40°C

ΔQ = m_material * c * ΔT

So, we can equate the two quantities of heat to find c:

m_water * c_water * ΔT = m_material * c * ΔT

c = (m_water * c_water * ΔT) / (m_material * ΔT)

the above expression yields  temperature c = 0.20 kcal/kg * C°.

The first container's mass and temperature are multiplied together, and the result is added to the second container's mass and temperature to determine the mixture's water temperature. Finally, divide that outcome by the combined water masses in each container.

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Answer:

Distance: 4.6km Displacement= -0.2km

Explanation:

Total distance: 1.5+2.4+0.7= 4.6 km

Displacement: 1.5-2.4+0.7= -0.2km

The displacement may also be 0.2km, it just depends on if it wants it negative or not.

Tiana displacement is 0.2 km in the opposite direction, while her distance covered is 4.6 km

Given that Tiana's original direction be the positive direction.

Displacement is a vector quantity. That is, we will consider both the magnitude and direction.

As Tiana jogs 1.5 km along a straight path and then turns and jogs 2.4 km in the opposite direction, Her displacement = 1.5 - 2.4

As She then turns back and jogs 0.7 km in the original direction,

Displacement = 1.5 - 2.4 + 0.7

Displacement = - 0.2 km ( that is, in the opposite direction.)

Distance is a scalar quantity. That is, we will only consider the magnitude.

Tiana total distance = 1.5 + 2.4 + 0.7

Total distance = 4.6 km

Therefore, her displacement is 0.2 km in the opposite direction, while her distance covered is 4.6 km

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The time it takes for a pulse of light to pass through a glass plate that is 6 cm thick is 0.00000002 seconds.

This is because light travels at a speed of approximately 299,792,458 meters per second in a vacuum (or air), but it slows down when passing through a material like glass or water. The speed at which light travels through a material is known as its refractive index, which is the ratio of the speed of light in a vacuum to the speed of light in the material. The refractive index of glass is about 1.5, which means that light travels through glass at about two-thirds of the speed at which it travels through air. Therefore, to calculate the time it takes for light to pass through a 6 cm thick glass plate, we need to divide the thickness of the glass plate by the speed of light in glass. Here's the calculation:Speed of light in glass = (speed of light in vacuum) ÷ (refractive index of glass)Speed of light in glass = 299,792,458 m/s ÷ 1.5Speed of light in glass = 199,861,639 m/sTime taken for light to pass through 6 cm of glass = (thickness of glass) ÷ (speed of light in glass)Time taken for light to pass through 6 cm of glass = 0.06 m ÷ 199,861,639 m/sTime taken for light to pass through 6 cm of glass = 0.00000002 s.

Therefore, it takes a pulse of light 0.00000002 seconds to pass through a glass plate that is 6 cm thick.

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Answer:

1/2 m v^2 = G M m / R         speed of object at surface of earth

v^2 = 2 G M / R        escape speed needed

V = 3 v     if original speed = 3 * escape speed

v^2 / 9 = 2 G M / R

v^2 = 18 G M / R    where v is initial speed

v^2 = G M / R  * (18 - 2) = 16 G M / R     very far from earth

v = (16 G M / R)^1/2

v = (16 * 6.67E-11 * 5.98E24 / 6.37E6)^1/2

v = 31650 m/s = 19.7 mi/sec

When a particle is projected from the surface of Earth with a speed equal to 3 times the escape speed, its final speed when very far from Earth will be 2 times the escape speed.

The escape speed is the minimum speed required for an object to overcome Earth's gravitational pull and move indefinitely away from it.

When a particle is projected with a speed 3 times the escape speed, it has more than enough energy to escape Earth's gravity.

As the particle moves away from Earth, it loses some of its kinetic energy due to Earth's gravitational force. Eventually, when the particle is very far from Earth, it will have lost an amount of kinetic energy equal to the escape speed.

Summary: When a particle is projected with a speed 3 times the escape speed and reaches a point very far from Earth, its speed will be 2 times the escape speed.

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Answer:

The difference in the concentration of a substance between two areas is called the concentration gradient . The bigger the difference, the steeper the concentration gradient and the faster the molecules of a substance will diffuse. The direction of diffusion is said to be 'down' or 'with' the concentration gradient.

Explanation:

In the beaker with -0.4 MPa solution (at equilibrium): Ψp = 0 MPa

In the given scenario:

- When a plant cell is immersed in distilled water, its Ψs (osmotic potential) is -0.7 MPa, and its Ψ (pressure potential) is 0 MPa.

- Ψp (turgor pressure) can be calculated by subtracting Ψ from Ψs.

Therefore, in this case, the cell's Ψp would be -0.7 MPa.

If the same plant cell is placed in an open beaker of a solution with a Ψ of -0.4 MPa, at equilibrium, the Ψp of the cell would be 0 MPa. At equilibrium, the Ψp of the cell becomes zero because the cell's water potential (Ψ) equals the external solution's water potential (Ψ) in an open system.

In summary:

- In distilled water: Ψp = -0.7 MPa

- In the beaker with -0.4 MPa solution (at equilibrium): Ψp = 0 MPa

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The dose received when moving from 1 meter to 2 meters from a radiation source decreases as the distance from the source increases.

The dose received from a radiation source is inversely proportional to the square of the distance from the source. This relationship is known as the inverse square law. According to the inverse square law, when the distance from the source is doubled (from 1 meter to 2 meters), the dose received is reduced to one-fourth of the original dose.

This is because the intensity of radiation decreases with distance due to the spreading of radiation over a larger area as it travels away from the source. As the distance from the source increases, the radiation spreads out and becomes less concentrated, resulting in a decrease in the dose received.

Therefore, when moving from 1 meter to 2 meters from a radiation source, the dose received is reduced by a factor of four due to the inverse square law. It is important to maintain a safe distance from radiation sources to minimize exposure and potential health risks.

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During daytime, the positions of the three bodies - the Sun, Moon, and Earth - are as follows: The Sun is located above the horizon, providing the primary source of light and illuminating the sky.

The Earth is beneath the Sun, with the observer standing on its surface. The Moon, although present in the sky, may or may not be visible, depending on its phase and position relative to the Sun and Earth.

During nighttime, the positions change. The Sun is located on the opposite side of the Earth, causing the sky to darken. The Moon may be visible, appearing in various phases depending on its position in its orbit around the Earth.

Overall, the positions of the Sun, Moon, and Earth change throughout the day and night due to the rotation and orbiting motion of the Earth and Moon.

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When an emission line of helium from a galaxy is shifted toward red, it means that the galaxy is moving away from the viewer and is denoted as option D.

This refers to the systems of stars and interstellar matter that make up the universe which are gravitationally bound together and are made up of four main components which are:

When an emission line of helium from a galaxy is shifted toward red, there is a displacement to a longer wavelengths and this alteration is referred to as a doppler shift.

Moving away from the view means that the galaxy will be viewed in the red spectrum of the visible light which is a part of the electromagnetic spectrum.

This is therefore the reason why option D was chosen as the most appropriate choice.

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-1.6 N

Split the forces into those in the x-direction and those in the y-direction. Since the book is not accelerating upward or downward, the net force in the y-direction is zero. Add the two forces in the x-direction (applied force and kinetic friction). This is the net force.

See details:

Answer:

The initial energy emission occurs by 80% or more in the form of gamma rays but these are quickly absorbed and dispersed mostly by air in little more than a microsecond, converting gamma radiation into thermal radiation (thermal pulse ) and kinetic energy (shock wave) which are actually the two dominant effects in the initial moments of the explosion. The rest of the energy is released in the form of delayed radiation (fallout or fallout) and is not always counted when measuring the performance of the explosion.

Explanation:

High altitude explosions produce greater damage and extreme radiation flux due to lower air density (photons encounter less opposition) and consequently a higher blast wave is generated.

Answer:

This happens because while fusing some of the mass of the helium nuclei gets converted to energy to fuel the fusion.

Explanation:

Answer:

a) a = 6.72 10⁻⁵ m,  b)  the slit (a) is smaller, which represents a wider pattern

Explanation:

In is a diffraction experiment since we have a single slit, it is explained by the equation

          a sin θ = m λ

where a is the width of the slit

The diffraction pattern is characterized by a very intense central maximum, with a value of 5.0 cm, therefore the distance from the center to the first zero is y = 5.0 / 2 cm = 2.5 10⁻² m

let's use trigonometry to enter the angle

         tan θ = y / L

         tan θ = sin θ / cos θ = sin θ

         sin θ = y / L

substituting into the equation

          a y / L = m λ

the first maximum occurs for m = 1

          a = λ L / y

let's calculate

          a = 560 10⁻⁹ 3.0 / 2.5 10⁻²

          a = 6.72 10⁻⁵ m

b) if the width a of the slit (a) is smaller

        sin θ = m λ / a

therefore the sinus increases, which implies a greater angle, which represents a wider pattern

c) if the distance to the screen (L) goes away

           y = m λL / a

If L increases the width of the pattern they also increase of course the intensity must be less

d) If the wavelength increases

    In this case the width of the pattern also increases

e) What happens if the light passes through two slits in this case we have two diffraction patterns one centered in each slit and the resulting pattern is the sum of these patterns, this sum gives the double slit interference that characterizes a series of slits of equal height

Simple diffusion of a molecule down its concentration gradient requires an input of energy to the system is false.

Diffusion is a type of molecule movement down its concentration from a higher concentration to a lower concentration. Because of that, it doesn’t require the energy (ATP) from respiration. The molecule only uses kinetic energy. Based on these characteristics, diffusion is included in passive transport.

Diffusion can either be simple diffusion or be facilitated by another molecule. Simple diffusion is the movement of molecules along their concentration gradient without the direct involvement of any other molecules, while facilitated diffusion is the transport of molecules via a protein membrane.

Thus, simple diffusion doesn’t need energy for regulating the molecule passing through the membrane.

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Answer:

The power will be "250 watt". A further explanation is given below.

Explanation:

The given values are:

Force,

F = 50 N

Displacement,

d = 20 m

Time,

t = 2.0 seconds

Whenever the block is pulled, the angle will be "0" i.e., Cos0° = 1

Now,

The work will be:

= \(Force\times displacement\times \Theta\)

On substituting the given values, we get

= \(50\times 10\times Cos0^{\circ}\)

= \(50\times 10\times 1\)

= \(500 \ Newton\)

Now,

The Power will be:

= \(\frac{Work \ done}{time}\)

= \(\frac{500}{2.0}\)

= \(250 \ watt\)