A mother sees that her child's glasses prescription is 0. 870 D. The glasses are 1. 95 cm from the eyes. What is the child's near point (in cm)? (Assume the near point of an unaided eye is normally 25 cm. )

The mass of methane will produce as much energy as a single gram of uranium-235 1,287 kilograms of methane. Option D is correct.

Uranium, with the atomic number 92 and the symbol U in the periodic table, is a weakly radioactive element. One of the heavy metals that may be used as a concentrated energy source is uranium.

Given data;

⇒One mole of U-235 = 235 grams

=> 1 gram of U-235 = 1/235 moles

⇒1 mole of U-235 = 6.023 x 10²³ atoms

The no of atoms is;

=> 1/235 moles of U-235

⇒N = 6.023 x 10²³/235 atoms

⇒N=25.6 x 10²⁰ atoms

If one atom of U-235 gives is 189 x 10⁶ eV energy,25.6 x 10²⁰ atoms of U-235 gives;

=> 25.6 x 10²⁰ atoms of U-235 gives;

E = 25.6 x 10²⁰ x 189 x 10⁶

E= 4.8 x 10²⁹ eV energy

One methane molecule produces;

E = 10 eV of energy

=> To produce 4.8 x 10²⁹ eV energy, no. of molecules required;

= 4.8 x 10²⁸

6.032 x 10²³ molecules of methane = 16 gms

=> 4.8 x 10²⁸ molecules of methane = 16 x 4.8 x 10²⁸/ 6.032 x 10²³ gms

m= 12.75 x 10⁵ gms

m= 1275 kilograms of methane

m≅ 1287 kilograms of methane

1 gram of U-235 has the same amount of energy as 1287 kilograms of methane.

Hence option D is correct,

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Explanation:

The electrical forces on each body now becomes doubled when the charge on one of the bodies is doubled. When two charged bodies are separated by a distance d, they exert electrical forces on each other.

Electrical forces, also known as Coulomb forces, are a type of non-contact force produced by the presence of electrically charged particles. Electrical forces are fundamental forces that are responsible for keeping the electrons in the atom and the nucleus together.

According to Coulomb's law, the electric force acting between two charged particles is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them. The electrical forces acting between two charged bodies are affected by the amount of charge they possess, the distance between them, and the medium that they are present in.

When the charge on one of the bodies is doubled, the electrical forces on each body now become doubled. Thus, the force exerted by one body on the other and vice versa becomes two times the initial force.

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The velocity of a particle at time t is 4t³- 7, at time t = 3 is 101 ft/sec, and at rest is ∛7/4 sec.

The position of a particle at time t is

s(t) = t⁴ - 7t + 22, where t > 0

(A)  Velocity at time t is

V(t) = s'(t)

Or, V(t) = 4t³ - 7 × 1 + 0

Or, V(t) = 4t³- 7

Hence, the velocity at time t is 4t³- 7.

B) Velocity ar time t = 3 is

V(3) = 4(3)³- 7

Or, V(3) = 101 ft/sec

Hence, the velocity at time t = 3 is 101 ft/sec.

(C) When particle is at rest, V(t) = 0

Then, 4t³ - 7 = 0

Or, t³ = 7/4

Or, t = ∛7/4 sec

Therefore, the velocity at rest is ∛7/4 sec.

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Answer:

a covalent

Explanation:

ionic bonding involves only the transfer of electrons but not exchange of electrons

Answer:

D. Solution

Explanation:

Sugar dissolved in water is an example of solution.

A solution is a homogenous mixture of solutes and solvents.

In a solution the solute particles ae distributed uniformly in the solvents. The solute is the substance and it is the sugar here that is dissolved to make a solution.

The solvent is the water in this instance that helps to dissolve the solute.

Answer:

D. Solution

Explanation:

Dissolving sugar in water is an example of a physical change. Here's why:

A chemical change produces new chemical products. In order for sugar in water to be a chemical change, something new would need to result.

(a) The kinetic energy of the cart when it moves is 2/3 the way down is 1/3mgh.

(b) The total mechanical energy of the cart at the given height of 5 m is 5mg.

The potential energy of the cart when it is 2/3 way down the given height of 5 m is calculated as follows;

ΔP.E = mghf - mgh₀

ΔP.E = mg(hf - h₀)

ΔP.E = mg(2h/3 - h)

ΔP.E = -¹/₃mgh

ΔK.E = -ΔP.E

ΔK.E = ¹/₃mgh

M.A = P.E + K.E

M.A = ²/₃mgh + ¹/₃mgh

M.A = mgh

M.A = mg(5)

M.A = 5mg

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0.5Ω

Since different currents are passing through the resistors, then the resistors are most probably connected in parallel. This also means that the same voltage will pass across them.

Using Ohm's law, the voltage across a resistor in a circuit is given by;

V = I(R + r)            -----------(i)

For the 1ohm resistor, the voltage across it is given by;

Where;

I = current passing through the 1 ohm resistor = 0.6A

R = resistance of the 1 ohm resistor = 1Ω

r = internal resistance of the cell = r

Substitute these values into equation (i) as follows;

V = 0.6(1 + r)                 -------------------(ii)

For the 4.0ohm resistor, the voltage across it is given by;

Where;

I = current passing through the 4.0 ohms resistor = 0.2A

R = resistance of the 4.0 ohms resistor = 4.0Ω

r = internal resistance of the cell = r

Substitute these values into equation (i) as follows;

V = 0.2(4.0 + r)                 -------------------(iii)

Now solve equations (ii) and (iii) simultaneously;

V = 0.6(1 + r)

V = 0.2(4.0 + r)

Substitute the value of V in equation (ii) into equation (iii). Therefore, we have;

0.6(1 + r) = 0.2(4.0 + r)

Solve for r

0.6 + 0.6r = 0.8 + 0.2r

0.6r - 0.2r = 0.8 - 0.6

0.4r = 0.2

r = \(\frac{0.2}{0.4}\)

r = 0.5

Therefore, the internal resistance of the cell is 0.5Ω

Answer:

Por ela ter batido na trave, não tem como voltar 2x mais forte, por que toda ação correspondente a uma reação de igual intensidade, mas que atua no sentido oposto

Explanation:

Answer:

The mass of the block of material is 3 x 10³⁷ g/mol

The charge of the material is  4.8 x 10⁸ C

Explanation:

Given;

number of protons of the material, P = 3 x 10²⁷

number of neutrons in the material, N = 3 x 10³⁷

number of electrons in the material, E =  3 x 10²⁷

The mass of the block of material is calculated as follows;

M = P + N

M =  3 x 10²⁷ +  3 x 10³⁷

M =  3 x 10³⁷ g/mol

The charge of the material is calculated as follows;

charge of 1 electron = 1.6 x 10⁻¹⁹ C

charge of  3 x 10²⁷ electrons =  3 x 10²⁷ electrons   x   1.6 x 10⁻¹⁹ C

                                                = 4.8 x 10⁸ C

Any circuit diagram given the funda is same .

Answer:

see  picture
Sample Response: The lightbulb will light because this is a parallel circuit. Even though the switch is open in one branch, the branch the lightbulb is in forms a closed circuit, allowing the current to flow through the bulb.

Explanation:

The maximum height reached by the ball is 1042.9 m and the range of the ball is 543.98 m.

The given problem can be solved using projectile motion. Projectile motion is a form of motion that occurs when an object is thrown near the surface of the earth and moves along a curved path due to the influence of gravity. Here, a ball is thrown into the air at an angle of 70 degrees above the horizontal with an initial velocity of 60 m/s from a 50 m high building. We need to find the maximum height reached by the ball and the range of the ball.

Let's first find the time taken to reach the maximum height. We know that,Initial vertical velocity

u = usinθ

= 60sin70°

= 57.66 m/s

Acceleration due to gravity g = 9.8 m/s²

Maximum height h is given by the formula,

h = u²sin²θ/2g

= 57.66²sin²70°/2×9.8

= 1042.9 m

Now, we can find the time taken to reach the maximum height using the formula

v = u + gt0

= v - u/g

= 0 - 57.66/9.8

= 5.87 s

So, the time taken to reach the maximum height is 5.87 s.

Using the formula, Range

R = u²sin2θ/g

= 60²sin2(70°)/9.8

= 543.98 m

Therefore, the maximum height reached by the ball is 1042.9 m and the range of the ball is 543.98 m.

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The time taken by Kamal's family to drive on the second day is 6.45 hours.

What is speed?

Speed is defined as the ratio of the time it takes for a body to cross a distance to the time it takes.

The time is calculated as:-

For 4 hours of driving at an average speed of 60 miles per hour, the distance covered is,

d = 60 x 4 = 240miles

Miles remaining for the second day is,

627 - 240 = 387 miles

Time taken to cover 387 miles second day is,

T = 387 / 60 = 6.45 hours

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Answer:

in physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies. example a familiar example is a playground swing, which acts as a pendulum.

hope this helped!

A 40 kg crate is pulled at a constant velocity. The coefficient of kinetic friction is 0.5 and the crate moves 7 m . The amount of work done is 140 joule.

When an object is moved over a distance by an external force, at least a portion of that force must be applied in the direction of the displacement.

By multiplying the length of the path by the component of the force acting along the path, work can be calculated if the force is constant. The work W is equal to the force f times the distance d, or W = fd, to mathematically describe this idea.

The work is W = fd cos if the force is applied at an angle of to the displacement. Performing work on a body involves moving it in its entirety from one location to another as well as.

Therefore, A 40 kg crate is pulled at a constant velocity. The coefficient of kinetic friction is 0.5 and the crate moves 7 m . The amount of work done is 140 joule.

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Answer:

Explanation:

It increases the speed because of gravitational potential energy. Gravitational potential energy depends on height, mass, and speed which would help increase the speed.

Answer:

It increases speed because gravitational pull

Explanation:

When objects fall to the ground, gravity causes them to accelerate. Acceleration is a change in velocity, and velocity, in turn, is a measure of the speed and direction of motion. Gravity causes an object to fall toward the ground at a faster and faster velocity the longer the object falls.

Answer:

I want to say decomposers, because they break down plants that the herbivores eat, and they can also decompose the remains of a scavenger, herbivore, OR carnivore, that was killed and eaten by a carnivore, and maybe even found and eaten by a scavenger. I'm sorry if it's not correct, that's just what my brain has decided right now

Answer:

The answer is number 4. Decomposers

Explanation:

Hope this helps!!

Hi there!

We can use the work-energy theorem to solve.

Recall that:
\(E_i = E_f\)

The initial energy equals the final energy (Conservation of Energy). However, we must take into account energy dissipated due to friction in this instance.

The energy lost due to friction is equivalent to the work done by friction. Recall the following:

The work due to a force is:
\(W = F \cdot d \\\)

Since the displacement is in the same direction as the force, the dot-product becomes Fd.

The work due to friction then becomes:

\(W_f = \mu mgdcos\theta\)
The work due to friction is SUBTRACTED from the initial potential energy.

Initial energy = GPE = mgh

Final energy = KE

Therefore:

\(\boxed{mgh - \mu mgdcos\theta = KE}\)

Answer:

1.01×10^20 molecules of ozone.

Explanation:

Data obtained from the question include:

Volume (V) = 2 L

Temperature (T) = 275 K

Pressure (P) = 1.89×10¯³ atm

Gas constant (R) = 0.0821 atm.L/Kmol

Number of mole (n) of ozone =.?

Using the ideal gas equation, we can obtain the number of mole of ozone as follow:

PV = nRT

1.89×10¯³ x 2 = n x 0.0821 x 275

Divide both side by 0.0821 x 275

n = (1.89×10¯³ x 2) /(0.0821 x 275)

n = 1.67×10¯⁴ mole.

Therefore the number of mole of ozone in 2 L of air is 1.67×10¯⁴ mole.

Finally, we shall determine the number of molecules present in 1.67×10¯⁴ mole of ozone.

This can be obtained as follow:

From Avogadro's hypothesis, 1 mole of any substance contains 6.02×10²³ molecules. This implies that 1 mole of ozone contains 6.02×10²³ molecules.

If 1 mole of ozone contains 6.02×10²³ molecules,

therefore, 1.67×10¯⁴ mole of ozone will contain = 1.67×10¯⁴ x 6.02×10²³ = 1.01×10^20 molecules.

Therefore, 1.01×10^20 molecules of ozone are present in 2 L of air.

(3)False:a net force causes no change in an object's motion

(4)True: If Manuel exerts a force of 10 N to push a desk to the rigth at the same tiem Lynn exerts a force of 15 n to push the desk to the left , the desk will move to the left

Explanation

Step 1

(3)

Force is a push or pull on an object that produces acceleration in the body on which it acts

Newton's second law states that the time rate of change of the momentum of a body is equal in both magnitude and direction to the force imposed on it.

therefore, the answer is

False a net force causes no change in an object's motion

Step 2

(4)

a) Diagram:

to find the net force, add the vectos( let positive to the rigth)

as the net force is negative,object willmove to the left,so

the answer is

True: If Manuel exerts a force of 10 N to push a desk to the rigth at the same tiem Lynn exerts a force of 15 n to push the desk to the left , the desk will move to the left

I hope this helps you

In free fall, an object develops under the influence of gravitational force only. The only boosting is the acceleration of gravity 'g'. None of the other force, including air resistance, is drama on such an object.

interestingly, an object in free fall does not certainly need to be falling (that is, moving downwards).

For example, the Moon's motion smug all of the conditions listed above: there is no other force acting on it other than gravity (it is being pulled towards the Earth), and there is no air resistance, as there is no air in space.

By the definition of velocity, we can find the velocity of a falling object is:

v=v0 +gt

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For the spring system:

a. The spring constant can be calculated using Hooke's Law, which is represented as F = kx,

where k = spring constant. In this case, the weight of the 2kg mass is providing the force to extend the spring.

Given that the weight of the mass, w = mg = 2kg × 9.8 m/s² = 19.6 N (force), and the extension of the spring, x = 15 cm = 0.15 m, rearrange the equation to solve for k.

k = F / x = 19.6 N / 0.15 m = 130.67 N/m.

b. The frequency of oscillation for a mass-spring system undergoing simple harmonic motion can be calculated using the formula f = 1/(2π) × √(k/m),

where f = frequency, k = spring constant, and m = mass.

Substituting the given values:

f = 1/(2π) × √(130.67 N/m / 2 kg) = 0.52 Hz.

c. The displacement of a mass undergoing simple harmonic motion is described by the equation x = A × cos(2πf × t + Ф),

where A = amplitude, f = frequency, t = time, and Ф = phase angle.

Here, A = 15 cm = 0.15 m (additional stretch from the equilibrium position), f = 0.52 Hz (from part b), t = 2 s, and because the object was released from its maximum displacement, the phase angle Ф = 0.

x = 0.15 m × cos(2π0.52 Hz × 2 s + 0) = -0.15 m. This means that at t = 2s, the object will be 15cm above the equilibrium position (since x is negative).

d. Given that the new frequency is half the initial frequency, write f_new = f_old / 2 = 0.52 Hz / 2 = 0.26 Hz. Use the formula for the frequency of oscillation, f = 1/(2π) × √(k/m),

where now m = total mass (2 kg + m_unknown).

Rearranging this formula to solve for m_unknown and substituting the known values:

m_unknown = k / (4π² × f_new²) - 2 kg = 130.67 N/m / (4π² × (0.26 Hz)²) - 2 kg = 4 kg. So the unknown mass added was 4 kg.

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The name for a burst of activity on an EEG in the early stages of sleep is "sleep spindle".

A burst of brain activity during non-rapid eye movement (NREM) sleep is known as a sleep spindle and can be seen on an electroencephalogram (EEG). Although it can occur in other NREM sleep stages as well, it is a hallmark of Stage 2 sleep.

Sleep spindles are characterized by a burst of rhythmic brain activity that spans from 11 to 16 Hz and are short (often lasting only a few seconds). The thalamus, a region of the brain that is essential for transmitting sensory data to the cerebral cortex, is the source of this activity. The thalamus absorbs sensory input during sleep and modifies the information flow to the cortex, enabling the brain to filter out unimportant inputs and concentrate on significant ones.

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Answer:

false

Explanation:

The statement "An orbiting satellite experiences no force due to the Earth's gravity." is a False statement. This is further explained below.

Generally, Gravity is simply defined as the force that pulls items toward the center of a planet or other entity.

In conclusion, an orbiting satellite experiences force due to the Earth's gravity.

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The valid combinations are:

Total resistance for a circuit in series is R_T = R1 + R2 + R3 + ...

Question 1

To determine the valid combinations of resistors for a circuit with a total resistance of 21, find combinations where the sum of the individual resistances equals 21. Analyze each option:

5, 12, and 4:

Total resistance = 5 + 12 + 4 = 21 (Valid combination)

7, 7, and 7:

Total resistance = 7 + 7 + 7 = 21 (Valid combination)

3, 3, and 3:

Total resistance = 3 + 3 + 3 = 9 (Invalid combination)

5, 5, and 5:

Total resistance = 5 + 5 + 5 = 15 (Invalid combination)

Therefore, the valid combinations are:

5, 12, and 4

7, 7, and 7

Question 2:

Regarding the second question, the equation that calculates the total resistance for a circuit in series is:

R_T = R1 + R2 + R3 + ...

So, the correct option is:

R_T = R1 + R2 + R3 + ...

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Answer:

4.55 seconds

Explanation:

Speed=distance / Time

So Time = Distance /speed

=1550/340

Specific heat capacity is the amount of energy needed to raise the temperature of a unit mass of a substance by one degree Celsius (or Kelvin).

We know that the heat lost by the object is gained by the water

m1c1ΔT1 = m2c2ΔT2

Where, m1 = Mass of the object

c1 = Specific heat capacity of the object

ΔT1 = Change in temperature of the object

m2 = Mass of the water

c2 = Specific heat capacity of the water

ΔT2 = Change in temperature of the water

We know that density of water = 1000 kg/m³

Density of object = Mass/Volume

⇒ Volume of the object = Mass/Density of the object

Given, Mass of the object = 0.075 kg Density of the object = ?

Volume of the object = Mass/Density of the object

                                   = 0.075 kg/ Density of the object

Initial temperature of water, T2 = 25 Celsius

Final temperature of water, T1 = 29 Celsius

Mass of the water, m2 = 0.15 kg

\(m1c1ΔT1 = m2c2ΔT2\\⇒ 0.075 kg × c1 × (-4) Celsius\\ = 0.15 kg × 4186 J/kg°C × 4 Celsius\\⇒ -0.3c1 = 25116 J/°C⇒ c1 = -25116 J/°C / -0.3 = 83720 J/°C\)

The specific heat capacity of the object is 83720 J/°C which can also be written as J/(kg°C) by dividing the answer by the mass of the object.

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The angle of incidence in the glass is approximately 31.8°.

To find the angle of incidence in the glass, we can use Snell's law, which states that the ratio of the sines of the angles of incidence and refraction is equal to the ratio of the indices of refraction:

n1 * sin(angle of incidence) = n2 * sin(angle of refraction)

In this case, n1 is the index of refraction for flint glass (1.61), n2 is the index of refraction for ethanol (1.36), and the angle of refraction in ethanol is 27.2°.

Plugging in these values into Snell's law, we get:

1.61 * sin(angle of incidence) = 1.36 * sin(27.2°)

To find the angle of incidence, we can rearrange the equation:

sin(angle of incidence) = (1.36 * sin(27.2°)) / 1.61

Now, we can solve for the angle of incidence by taking the inverse sine (or arcsine) of both sides:

angle of incidence = arcsin((1.36 * sin(27.2°)) / 1.61)

Calculating this value, the angle of incidence in the glass is approximately 31.8°.

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c. weight.

Explanation:

I had the exact same question

a change in gravitational force affects weight. The correct answer is: c. Weight

The gravitational force is given by the law of universal gravitation

         F = \(G \frac{M m}{r^2}\)

where F is the force, G the constant of universal attraction, M and m the mass of the two bodies, r the distance between the bodies

In the case that a body is lying on the surface of the planet, the distance is the radius of the planet, in this case the radius of the Earth

       r = R_e  

       F = \(G \frac{M m}{R_e^2}\)

For convenience we can define a new variable called acceleration of gravity (g)

       g = \(G \frac{M}{R_e^2}\)

we substitute

      F = g m

This amount is called body weight, so a change in gravitational force creates a change in weight, therefore the correct answer is: C Weight

In conclusion a change in gravitational force affects weight, therefore the correct answer is:  c. Weight

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Answer:

The water acts like a lubricant therefore has a smooth motion over the ice.