Which of these is only a physical change?
A. Melting a solid
B. Burning
C. Rusting
D. Forming a precipitate

When the acceleration is three times as large, the mass of the new block will be one-third the initial mass.

The acceleration of the block is the rate of change of velocity of the block with time.

The magnitude of the acceleration of each block can be obtained by applying Newton's second law of motion as follows;

F = ma

m = F/a

where;

When the acceleration is three times as large, the mass of the new block is calculated as;

m = F/3a

m = 1/3 (F/a)

new mass = one-third the initial mass

Thus, we can conclude that when the acceleration is three times as large, the mass of the new block will be one-third the initial mass.

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The tension in the strings are 31.47 and 19.25 N respectively.

Mass of the block, m = 3 kg

From the figure, consider the vertical components,

T₁ sin45° + T₂ sin30° = mg

(T₁/√2) + (T₂/2) = 3 x 9.8 = 29.4

Also, consider the horizontal components,

T₁ cos45° = T₂ cos30°

T₁/√2 = T₂ x√3/2

T₁ = T₂ x √3/2 x √2

So,

T₁ = 0.612T₂

Applying in the first equation,

(T₁/√2) + (T₂/2) = 29.4

(0.612T₂/1.414) + 0.5T₂ = 29.4

0.434 T₂ + 0.5 T₂ = 29.4

0.934 T₂ = 29.4

Therefore, the tension,

T₂ = 29.4/0.934

T₂ = 31.47 N

So, the tension,

T₁ = 0.612 T₂

T₁ = 0.612 x 31.47

T₁ = 19.25 N

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If the cloud is transparent, milky, thin layers, rain within the next 2 hours, then the cloud you are seeing is most likely a type of altocumulus cloud.

Altocumulus clouds are generally characterized by their white or gray color, and can sometimes appear milky or translucent. They often form in layers, and can be thin or thick depending on the conditions.

Altocumulus clouds are typically found at medium altitudes, between 6,500 and 20,000 feet and are often associated with unsettled weather conditions.

While they don't necessarily indicate that rain is imminent, altocumulus clouds can be a sign that a change in the weather is on the way.

Thus, if it is likely to rain in the next 2 hours, then the cloud must be altocumulus clouds.

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Answer:

"The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside. ... The only way to use energy is to transform energy from one form to another."

Explanation:

Brainliest?

Answer:

b

Explanation:

Answer:

I = 0.483 kgm^2

Explanation:

To know what is the moment of inertia I of the boxer's forearm you use the following formula:

\(\tau=I\alpha\)  (1)

τ: torque exerted by the forearm

I: moment of inertia

α: angular acceleration = 125 rad/s^2

You calculate the torque by using the information about the force (1.95*10^3 N) and the lever arm (3.1 cm = 0.031m)

\(\tau=Fr=(1.95*10^3N)(0.031m)=60.45J\)

Next, you replace this value of τ in the equation (1) and solve for I:

\(I=\frac{\tau}{\alpha}=\frac{60.45Kgm^2/s ^2}{125rad/s^2}=0.483 kgm^2\)

hence, the moment of inertia of the forearm is 0.483 kgm^2

The efficiency of motor is 90.58%.To determine the efficiency of the motor, we need to calculate the input power and the output power, and then divide the output power by the input power

The input power can be calculated using the formula:

Input Power = Voltage × Current

Given that the voltage is 230 V and the current is 24 A, we have:

Input Power = 230 V × 24 A

Input Power = 5520 W (or 5.52 kW)

The output power of the motor is given as 5 kW (since it is a 5 kW motor).

Now, we can calculate the efficiency:

Efficiency = (Output Power / Input Power) × 100%

Efficiency = (5 kW / 5.52 kW) × 100%

Efficiency ≈ 90.58%

Therefore, the efficiency of this motor is approximately 90.58%.

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The extension in the string when the particle hangs in equilibrium is e = mg/k. The constant n in the equation of motion is n = (2π/T)²m. The time it takes for the particle to enter simple harmonic motion is t = √(2§/g).

To find the extension in the string when the particle hangs in equilibrium, we need to consider the forces acting on the particle. The weight of the particle is mg, acting vertically downward. The tension in the string exerts an equal and opposite force, mg, to balance the weight. Since the particle is in equilibrium, the total force acting on it is zero.When the particle is dropped from a point below O, it will stretch the string due to its weight. Let's denote the extension of the string as e. The tension in the string will now be greater than mg because it needs to support the weight of the particle and provide the necessary centripetal force for the simple harmonic motion.The extension in the string is given by Hooke's law: F = kx, where F is the force, k is the modulus of the string, and x is the extension. In this case, the force is the tension in the string, and the extension is e. Thus, we have mg = ke. Rearranging the equation, we get e = mg/k.

To find the constant n in the equation of motion, › = -n?, we can use the fact that the period of simple harmonic motion is given by T = 2π√(m/k), where m is the mass of the particle and k is the spring constant. Comparing this with the equation of motion, we see that ω² = n/m. Since ω = 2π/T, we can substitute ω in terms of T and solve for n: n = (2π/T)²m.

To determine when the particle enters simple harmonic motion, we need to find the time it takes for the string to reach its equilibrium position. Since the particle is dropped from a point § meters below O, it will accelerate towards the equilibrium position due to the tension in the string. The time taken for this free-fall motion can be calculated using the equation of motion for constant acceleration: § = ½gt². Solving for t, we get t = √(2§/g).The amplitude of the simple harmonic motion is equal to the maximum displacement from the equilibrium position. In this case, the maximum displacement is equal to the initial dropped distance, § meters.To determine the time it takes for the particle to come to instantaneous rest for the first time, we need to find the time period of the simple harmonic motion. The time period, T, is given by T = 2π√(m/k). To find the time it takes to come to rest, we need to consider half of the time period, T/2.The amplitude of the simple harmonic motion is equal to the initial dropped distance, § meters. The time it takes for the particle to come to instantaneous rest for the first time is T/2, where T is the time period of the simple harmonic motion.

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Answer:

the position of the wood below the interface of the two liquids is 2.39 cm.

Explanation:

Given;

density of oil, \(\rho _o\) = 926 kg/m³

density of the wood, \(\rho _{wood}\) = 974 kg/m³

density of water, \(\rho _w\) = 1000 kg/m³

height of the wood, h = 3.69 cm

Based on the density of the wood, it will position across the two liquids.

let the position of the wood below the interface of the two liquids = x

Let the wood be in equilibrium position;

\(F_{wood} - F_{oil} - F_{water} = 0\\\\\rho _{wood} .gh - \rho _o .g(h-x) - \rho_w .gx = 0\\\\\rho _{wood} .h - \rho _o (h-x) - \rho_w .x = 0\\\\\rho _{wood} .h -\rho _o h + \rho _o x - \rho_w .x =0\\\\h (\rho _{wood} -\rho _o ) = x( \rho_w - \rho _o)\\\\x =h[\frac{ \rho _{wood} -\rho _o }{\rho_w - \rho _o} ]\\\\x = 3.69\ cm \times [\frac{974 - 926}{1000-926} ]\\\\x = 2.39 \ cm\)

Therefore, the position of the wood below the interface of the two liquids is 2.39 cm.

The potential energy of the lemming when it lands is 0.9108672 J.

To determine the potential energy (PE) of the lemming when it lands, we need to consider the conservation of energy. The potential energy of an object is given by the formula PE = mgh, where m is the mass of the object, g is the acceleration due to gravity, and h is the height.

Given:

Mass of the lemming (m) = 0.0780 kg

Height of the cliff (h) = 5.36 m

First, let's calculate the potential energy when the lemming is on the cliff. Using the given formula, we have:

PE = mgh

PE = 0.0780 kg * 9.8 m/s² * 5.36 m

PE = 0.413616 J

Next, we need to determine the final kinetic energy of the lemming just before it lands. We can use the equation for kinetic energy (KE) given by KE = (1/2)mv², where v is the velocity of the lemming.

Given:

Velocity of the lemming (v) = 4.84 m/s

Calculating the kinetic energy, we have:

KE = (1/2) * 0.0780 kg * (4.84 m/s)²

KE = 0.9108672 J

According to the conservation of energy, the potential energy at the top of the cliff is equal to the kinetic energy just before landing.

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Okay, here are the steps to solve this problem:

1) The seesaw is balanced when the sum of moments is 0.

2) The moment created by a force depends on the force and the perpendicular distance from the pivot point.

3) The 20 kg child sits 1 meter from the pivot. So its moment is 20 * 1 = 20 kg*m.

4) We want to find the distance for the 40 kg child to create a moment that balances the 20 kg child's moment.

5) So the moment of the 40 kg child must be 20 kg*m.

6) The moment depends on force and distance. We know the force is 40 kg.

7) So we set: 40 kg * distance = 20 kg*m

8) And solve for the distance: distance = 20 / 40 = 0.5 meters

Therefore, for the seesaw to balance with a 20 kg child 1 meter from the pivot and a 40 kg child on the other side, the 40 kg child should sit 0.5 meters from the pivot point.

Let me know if you have any other questions!

Answer:

The speed must a ball be thrown vertically from ground level to rise to a maximum height is 28.35 m/s.

Explanation:

Given;

maximum vertical height of the throw, H = 41 m

Apply the following kinematic equation;

V² = U² + 2gH

where;

V is the final speed with which the ball will rise to a maximum height

U is the initial speed of the ball = 0

g is acceleration due to gravity = 0

V² = U² + 2gH

V² = 0² + 2gH

V² =  2gH

V = √2gH

V = √(2 x 9.8 x 41)

V = 28.35 m/s

Therefore, the speed must a ball be thrown vertically from ground level to rise to a maximum height is 28.35 m/s.

Answer:

The answer is C ..

EXPLANATION:-

The amount of energy transferred between objects as a result of a difference in temperature.

Heat is the amount of energy transferred between objects as a result of a difference in temperature.

Heat is a form of energy. It is often measured in calories or joules. A calorie is the amount of heat required to raise the temperature of 1 gram of water by 1°C. One calorie is equal to 4.1855 joules. Heat tends to move from a warmer area to a colder one.

For example : Heat Engine.

Heat engine is used for converting the heat that is thermal energy into mechanical energy. The mechanical energy produced by heat engine is used for doing mechanical work.

Thus, Heat is the amount of energy transferred between objects as a result of a difference in temperature.

Hence, Option C is the correct answer.

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Answer:

D. Closed Surfaces

The gaussian surface could be a sphere and can be applied to flat surfaces, but it's always a closed surface.

Answer:

Explanation:

dropped from maximum height were vertical velocity is zero, the object would have a velocity of 25 m/s in a distance of

v² = u² + 2as

s = (v² - u²) / 2a

s = (25² - 0²) / (2(9.8))

s = 31.887755... m

s/h = 1 - ⅔

s/h = ⅓

h = 3s

h = 3(31.887755)

h = 95.6632...

h = 96 m

Grouping data refers to the process of categorizing or organizing data based on specific criteria or attributes.

It involves grouping similar data points together to gain a better understanding of patterns, relationships, and trends within the dataset. By grouping data, you can simplify complex information and derive meaningful insights from large amounts of data. The purpose of grouping data is to create subsets or clusters that share common characteristics.

This enables easier analysis, summarization, and comparison of data within each group. Grouping can be performed on various types of data, such as numerical, categorical, or time-based data. Grouping data allows for the exploration of data at different levels of granularity.

For example, you can group sales data by region to analyze regional performance, or group customer data by demographics to identify specific customer segments. This process helps in identifying outliers, detecting patterns, and making data-driven decisions.

Common techniques for grouping data include using functions like GROUP BY in SQL or utilizing data visualization tools to create charts or graphs that illustrate the grouped data. Grouping can be applied in various fields, such as marketing, finance, healthcare, and research, to uncover insights and support decision-making processes.

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Answer:

Agree

Explanation:

Regarding the aluminium foil, its actually a transparent material, allowing almost all light to pass through. Non-visible light, such as radio waves, x-rays, and gamma-energy photons, can most definitely can travel through wood too. So yeah agree.

Light can travel through transparent materials which we  can see through.  Materials like, wood, aluminums foil etc. are opaque to light and does not pass light through it. Hence, disagreeing to the statement.

A material is said to be transparent if light can pass through it. Thus light any of the phenomenon like transmission, absorption or reflection. A fraction of light transmitting through the material is absorbed by it.

Mirror, glass, water etc. are transparent and light can transmit through it. These materials can absorb light and reflect a portion. The amount of incident light that is absorbed by the material is dependent on its nature.

Objects that does not pass light through them are called opaque. They cant absorb or reflect light. Objects such as wood, aluminum foil, metals such  as iron etc. are opaque. Thus, the given statement is false.

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Answer:

Definition- Electric power is the rate at which electrical energy is transferred by an electric circuit.

Answer:

the rate at which electrical energy is transferred by an electric circuit.

Explanation:

Regarding memory, conscious is to explicit memory as unconscious is to implicit memory.

Answer:

Explanation:

The energy stored is E = 1/2 kx^2.

E1 = E2

1/2 k(1.3)^2 = 1/2 (2k)x^2

x^2 = 1/2 (1.3)^2

x = 1.3/sqrt(2) cm

x =0.919 cm

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Compression in a spring with twice the spring constant to store the same amount of energy is 0.919 cm

Energy is the ability or capability to do tasks, such as the ability to move an item (of a certain mass) by exerting force. Energy can exist in many different forms, including electrical, mechanical, chemical, thermal, or nuclear, and it can change its form.

Given spring is compressed 1.3 cm. Compression in a spring with twice the spring constant to store the same amount of energy is,

The energy stored is E = 1/2 kx².

E1 = E2

1/2 k(1.3)² = 1/2 (2k)x²

x^2 = 1/2 (1.3)²

x = 1.3/√2 cm

x = 0.919 cm

Compression in a spring with twice the spring constant to store the same amount of energy is 0.919 cm.

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Answer:

The energy is transferred to chemical and heat energy.

Explanation:

If you define "bouncing" as leaving the ground for any amount of time, the ball stops bouncing when the elastic energy stored in the compression phase of the bounce is not enough to overcome the weight of the ball. This is the proof of the answer i Hope this helps :)

Answer:

The value is \(V = 2 V\)

Explanation:

From the question we are told that

The length of the wire is \(l = 10 \ m\)

The current density is \(J = 4*10^6 \ A/m^2\)

The conductivity is \(\sigma = 2*10^{7} \ S/m\)

Generally conductivity is mathematically represented as

\(\sigma = \frac{l}{RA}\)

Here R is the resistance which is mathematically represented as

\(R = \frac{V}{I}\)

Here I is the current which is mathematically represented as

\(I = J * A\)

So

\(R = \frac{V}{ J * A}\)

And

\(\sigma = \frac{l}{\frac{V}{ J * A} * A}\)

=> \(\sigma = \frac{l}{\frac{V}{J}}\)

=> \(V = \frac{l * J}{\sigma }\)

=> \(V = \frac{10 * 4*10^6}{2*10^{7} }\)

=> \(V = 2 V\)

Answer:

v = 2 m/s.

Explanation:

From the given graph, it is clear that the position is bee is 8 m between 4 s to 6 s. It would mean that its displacement is equal to 0 because final position is equal to initial position.

Between 6 s to 8 s, its velocity is decreasing and it is calculated using slope. The slope of position time graph gives velocity of an object.

\(\text{slope}=v=\dfrac{8-4}{8-6}\\\\v=\dfrac{4\ m}{2\ s}\\\\v=2\ m/s\)

So, the velocity of the bee between 4 s to 8 s is 2 m/s.

The resistance of a platinum resistance thermometer is 200 Ω at 0°C and 255.8 Ω at the melting point. Using the resistance-temperature relationship and calculations, the estimated melting point is approximately 19.93°C.

The resistance of a platinum resistance thermometer is 200 Ω when placed in a 0°C ice bath and 255.8 Ω when immersed in a crucible containing a melting substance. To determine the melting point of the substance, we need to calculate the temperature at which the resistance reaches 255.8 Ω.

First, we find the temperature coefficient of resistance (α) using the formula α = (R - R₀) / (R₀ * T), where R is the resistance at the melting point, R₀ is the resistance at 0°C, and T is the temperature at the melting point.

Substituting the given values, we have α = (255.8 - 200) / (200 * T₀), where T₀ is the known room temperature of 20°C.

Calculating α, we find α ≈ 0.014.

Next, we use the resistance-temperature relationship equation R = R₀(1 + αT) to solve for the melting point temperature (T). Substituting the known values, we have 255.8 = 200(1 + 0.014 * T).

Simplifying the equation, we find 1.279 = 1 + 0.014T.

Solving for T, we get T ≈ 19.93°C.

Therefore, based on the given data, the estimated melting point of the substance is approximately 19.93°C.

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Answer:

Radius of curvature of the mirror = 250 cm

Explanation:

Given:

Object distance from mirror = 250 cm (u=-250)

Object distance appears in mirror = 250 cm (v=-250)

Find:

Radius of curvature of the mirror

Computation:

Using mirror formula

1/f = 1/v + 1/u

1/f = 1/(-250) + 1/(-250)

f = (-250/2)

f = -125 cm or 125 cm

Radius of curvature of the mirror = 2(f)

Radius of curvature of the mirror = 2(125)

Radius of curvature of the mirror = 250 cm

Answer:

the magnitude of the charge on the drop is 5.163 × 10⁻¹⁸  C

Explanation:

Given that;

mass of the drop m = 8.0×10⁻¹⁵ kg

distance d = 16 cm = 0.16 m

potential difference between the plates V = 2.44 kV = 2440 v

acceleration of gravity g = 9.81 m/s²

the magnitude of the charge on the drop = ?

weight is balanced by the electrostatic force

weight = mg = 8.0×10⁻¹⁵ kg × 9.81 m/s² = 7.848 × 10⁻¹⁴

we know that; V = Ed

E = V/d =  2440 / 0.16 = 15200 v/m

Electrostatic force = qE

so weight = qE

q = weight / E

q = 7.848 × 10⁻¹⁴ / 15200

q = 5.163 × 10⁻¹⁸  C

Therefore, the magnitude of the charge on the drop is 5.163 × 10⁻¹⁸  C

Explanation:

You can just use Pythagorean theorem to find the resultant mag

20^2 + 100^2 = R^2

mag of R = 102 m/s

The speed of the truck just before braking is 23.24 m/s.

The speed of the truck before braking is calculated by applying the third kinematic equation as shown below.

v² = u² - 2as

where;

When the truck stops, the final velocity = 0

0 = u² - 2as

u²  = 2as

u = √2as

u = √ ( 2 x 6 x 45 )

u = 23.24 m/s

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Air is used to pressurize water in a tank, and the pressure is then measured. by a multifluid manometer so Consequently, the air pressure in the tank is 129.45KPa.

In the physical sciences, pressure is defined as either the stress at a place within a confined fluid or the perpendicular force per unit area. The weight of the atm is atmospheric pressure, which is approximately 15 pounds per square inch at sea level. Each square meter of the Earth's surface is under pressure from the atmosphere.

atmospheric pressure (\(P_{atm\))=85.6kPa

 \(P_{atm\)=85600Pa

density of water=\(\rho =\)1000 kg/\(m^3\)

density of oil(\(\rho_0\))=850kg/\(m^3\)

density of mercury(\(\rho_{m\))=13600 kg/\(m^3\)

height of water column(\(h_1\))= 0.1m

height of oil column from water level(\(h_2\))=0.2m

height of mercury column (\(h_3\))=0.35m

pressure at point B

\(P_B=P_{air} +\:\rho_0gh_1\: +\rho_wgh_2 \: \rightarrow(1)\)

\(P_B=P_{atm} +\:\rho_mgh_3\: \rightarrow(2)\)

\(P_{air} +\:\rho_0gh_1\: +\rho_wgh_2 \:=P_{atm} +\:\rho_mgh_3\:\)

\(P_{air} =\:-\rho_0gh_1\: -\rho_wgh_2 \:+P_{atm} +\:\rho_mgh_3\:\rightarrow(3)\)

\(\rho _mgh_3\)=13600x9.8x0.35=46648 Pa

\(\rho _0gh_1\) =850x9.8x0.1=833 Pa

\(\rho _wgh_2\) =1000x9.8x0.2=1960 Pa

By putting the value in eq.3

\(P_{air\)=85600+46648−833−1960 = 129455Pa

therefore pressure of air in the tank is 129.45KPa

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The change in motion, visible effects of the collision, and temperature increase would all serve as evidence that energy was transferred during the collision between the cart and the track after the removal of electrostatic forces.

If the electrostatic forces on the cart and track were suddenly removed and the cart hits the track, there would be several pieces of evidence indicating that energy was transferred during the collision.Firstly, there would be a noticeable change in the motion of the cart. The cart would decelerate as it collides with the track, and its velocity would decrease due to the loss of energy. This change in motion demonstrates that energy has been transferred from the cart to the track.

Secondly, there may be visible effects of the collision, such as deformation or damage to the cart or the track. This deformation or damage occurs because the energy transferred during the collision is transformed into other forms, such as heat or sound energy. These visible effects provide evidence of energy transfer.Additionally, there could be an increase in the temperature of the cart and/or the track due to the conversion of kinetic energy into thermal energy upon impact. This temperature change would be another indication that energy has been transferred.

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