A car travels from Kathmandu to Hetauda. The distance covered by it in 4hrs is
200km. Find the average speed of the car.
​

Lenses, which are pieces of curved, clear glass, were employed in early telescopes to focus light.

Curved mirrors are used by the majority of telescopes nowadays to collect light from the night sky. Light is focused by a telescope's mirror or lens' shape.

Astronomers use a telescope to observe distant things. Curved mirrors are used by the majority of telescopes, including all large telescopes, to collect and concentrate light from the night sky.

The original telescopes employed lenses, which are simply curved pieces of clear glass, to focus light. The "optics" of a telescope are the mirrors or lenses. Strong telescopes may view objects that are extremely faint and incredibly far away.

Therefore, Lenses, which are pieces of curved, clear glass, were employed in early telescopes to focus light.

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The energy is needed to evaporate 5 grams of water is 1670 kJ.

The energy is the ability to do work.

Energy required to change the phase of an object is mass times the latent heat of vaporization.

Q = mL

where, latent heat of vaporization L =334J/g

Given is the mass of water m =5g, then the energy needed will be

Q =5 x 334

Q =1670 kJ

Thus, the energy needed to evaporate water is 1670kJ.

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The minimum force needed to move the whale along a horizontal ramp, given that the whale has a mass of 1.90×10⁵ Kg is 856520 N

We'll begin by listing out the given parameters from the question. This is shown below:

To obtain the force needed to move the whale, we shall first obtain the normal reaction. This is shown below:

N = mg

N = 1.90×10⁵ × 9.8

N = 1862000 N

Finally, we shall determine the force needed. Details below:

F = μN

F = μN

F = 0.460 × 1862000

F = 856520 N

Thus, we can conclude that the force needed is 856520 N

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Answer:

a. an increase in the mass on the spring.

Explanation:

An increase in the mass on the spring will increase the period of an oscillating spring mass system.

Mathematically, the period of an oscillating spring mass system is given by the formula;

T = 2π √(m/k)

Where;

T is the period.

m is the mass of the spring.

k is the spring constant.

Hence, the mass of a spring is directly proportional to the period of oscillation of the spring.

This ultimately implies that, as the mass of the spring increases, the period of oscillation will increase. Similarly, the period of oscillation will decrease with an increase in the spring constant.

Important Formulas:

[tex]w=Fd[/tex]

work(measured in joules) = force(measured in newtons) * distance(measured in meters)

__________________________________________________________

Given:

[tex]m=42kg[/tex]

[tex]F=225N[/tex]

[tex]d=12m[/tex]

[tex]w=Fd[/tex]

__________________________________________________________

Finding work:

[tex]w=Fd[/tex]

[tex]w=225\times12[/tex]

__________________________________________________________

[tex]\fbox{w = 2700 Joules}[/tex]

(a) The magnitude of the car's normal force is 7,792.2 N.

(b) The mass of the car is 795.1 kg.

The weight of the car is calculated by applying Newton's second law of motion as shown below.

Mathematically, the formula for Newton's second law of motion is given as;

Ff = μW

where;

The weight of the car is calculated as follows;

W = Ff / μ

W = ( 6,000 N ) / ( 0.77 )

W = 7,792.2 N

Based on Newton's third law of motion, the weight of the car acting downwards is equal to normal force on the car, acting upward.

The mass of the car is calculated as follows;

W = mg

where;

m = W / g

m = ( 7792.2 ) / (9.8)

m = 795.1 kg

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The statement that is correct is that the contents of the cup form a mixture.

Though the question is incomplete but I would try to give you a good explanation as much as I can. We must recall that when we talk about a mixture, we have to note that the term mixture would refer to the combination of two or more substances that do not chemically react together.

In this case, we have been told that we have a water that was pure and then we add dirt to it. It is clear that the water and the dirt do not react in any way hence what we have formed is a mixture.

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Here's the solution,

A.) calculate work done :

we know,

[tex]weight \: = mass \times acceleration[/tex]

And,

[tex]work \: done = force \times dispacement[/tex]

B.) find power :

[tex]power = \dfrac{work \: done}{time} [/tex]

Answer:

work done=2000J and power=1000w

Explanation:

(a) Work done= Gravitational potential energy

W=mgh

Data,

m=10kg

h=20m

g=10N/kg

W=10kg*10N/kg*20m

W=2000J or 2kJ

(b). power=work done/time

P=2000/2

P=1000w

Answer:

Should be 17.8m/s

Explanation:

Initial momentum = Final momentum

(m1×v1)+(m2×v2)=(m1+m2)v since its an inelastic collision.

Answer:

Explanation:

Let the spring constant of spring A and B be k₁ and k₂ . Mass of box X and Y be m₁ and m₂ .

Force created in spring which is stretched by d is kd where k is spring constant .

At her lab in Orlando, Florida,

k₁ x .0204 m = m₁ g where g is acceleration due to earth's gravity

k₁ = 49 m₁ g

At a research station on the moon

k₁ x .34 x 10⁻² m = m₁ g₁ where g₁ is acceleration due to gravity at moon

k₁  = 294 .11 m₁ g₁

49 m₁ g = 294 .11 m₁ g₁

g = 6.0022  g₁

At a research station on the moon

k₁ x .54 x 10⁻² m = m₂ g₁

k₁ = 185.18 m₂ g₁

294 .11 m₁ g₁ = 185.18 m₂ g₁

1.588 m₁ =  m₂

1 )

At her lab in Orlando, Florida,

k₁ x d  = m₂ g , where d is the new stretch that is to be calculated .

185.18 m₂ g₁ d =m₂ g

185.18 d  g₁ = g

185.18 d  g₁ = 6.0022  g₁

d = .03241 m

= 3.24 cm .

2 )

At a research station on the moon

when Block Y is hanging from Spring B

k₂ x .013   = m₂ g₁

k₂ = 76.92 m₂ g₁

At her lab in Orlando, Florida,

Spring B stretch when Block X is hanging from it

k₂ d₁ = m₁ g

76.92 m₂ g₁ d₁ = m₁ g

76.92 m₂ g₁ d₁ = m₁ 6.0022  g₁

76.92 m₂  d₁ = m₁ 6.0022  

12.815  x  1.588 m₁ x  d₁ = m₁

d₁ = .049 m

= 4.9 cm .

In this exercise we have to use the knowledge of springs to calculate the distance from it, that way:

A)d=3.24 cm

B)d=4.9 cm

So, before starting the calculations, we have to organize the values ​​and put everything in function of a single unknown such as:

[tex]k_1 * 0.34 * 10^{-2} m = m_1 g_1\\ k_1 = 294 .11 m_1 g_1\\49 m_1 g = 294 .11 m_1 g_1\\g = 6.0022 g_1\\k_1 *0 .54 * 10^{-2} m = m_2 g_1\\k_1 = 185.18 m_2 g_1\\294 .11 m_1 g_1 = 185.18 m_2 g_1\\1.588 m_1 = m_2[/tex]

A) By calculating the distance we find that:

[tex]k1_1 * d = m_2 g\\185.18 m_2 g_1 d =m_2 g\\185.18 d g_1 = g\\185.18 d g_1 = 6.0022 g_1\\d = 0.03241 m= 3.24 cm[/tex]

B) So now calculating the distance from the lab to the moon, so:

[tex]k_2* 0.013 = m_2 g_1\\k_2 = 76.92 m_2 g_1\\k_2 d_1 = m_1 g\\76.92 m_2 g_1 d_1 = m_1 g\\76.92 m_2 g_1 d_1 = m_16.0022 g_1\\76.92 m_2 d_1 = m_1 6.0022\\12.815 * 1.588 m_1 * d_1= m_1\\d_1 = 0.049 m = 4.9 cm[/tex]

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Answer:

he is right its c

Explanation:

Answer:

a current that rapidly switches direction

Explanation:

Students are instructed in subject-specific classes by science professors. They develop lesson plans, assess student performance, and educate using lectures, technology.

The teacher who gives their best in order to develop the skills in all student of their class. A good teacher has to be a great command of his/her subjects.

He/she has to put their effort to improve the weak student of the class as well must appreciate the effort of good students.

The role of the teacher and the learner in a natural science and technology classroom​ is;

Students are instructed in subject-specific classes by science professors. They develop lesson plans, assess student performance, and educate using lectures, technology,

They also serve as role models for anticipated conduct in order to develop and maintain an ordered, disciplined classroom.

They must also be analytical since they must analyze kids' development and modify lesson plans for special-needs children.

They may create and sustain interpersonal ties with students, parents, other staff members, and administrators.

Hence the role teacher is to instruct the student, maintain discipline and educate using technology.

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The potential energy of a rock of mass 500 g, held at a height of 2 m above ground is 9.8J.

The formula for the gravitational potential energy of an object is:

PE = mgh

where m is the mass of the object, g is the acceleration due to gravity (approximately 9.8 m/s^2 on the Earth's surface), and h is the height of the object above the reference point.

So, in this case, we can plug in the given values to find the potential energy of the rock:

PE = (500 g) x (9.8 m/s^2) x (2 m)

The weight of the rock is m*g = 500 g * 9.8 m/s^2 = 4.9 N

Therefore,

PE = 4.9 N x 2 m = 9.8 J

Therefore, the potential energy of a rock of mass 500 g, held at a height of 2 m above ground is 9.8J.

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Answer:

Explanation:

From the given information:

The speed of a synchronous motor in relation to its frequency can be represented with the formula:

[tex]n_{sm}= \dfrac{120f_{se}}{P}[/tex]

where,

the electrical frequency [tex]f_{se}[/tex] is measured in Hz

the number of poles = P

For us to estimate the number of poles to have 50 Hz - 60 Hz Power, then we need to relate the frequencies of the above equation.

i.e

[tex]\dfrac{120(50 \ Hz)}{P_1}= \dfrac{120( 60 \Hz)}{P_2} \\ \\ \dfrac{6000 \ Hz}{P_1}= \dfrac{7200 \ Hz}{P_2} \\ \\ \dfrac{P_2}{P_1}=\dfrac{7200}{6000} \\ \\ \\ \dfrac{P_2}{P_1}= \dfrac{12}{10}[/tex]

Thus, we can conclude that 10 poles synchronous motor is attached with 12 poles synchronous generator in order to convert 50 Hz to 60 Hz power.

Answer:

58.7g  (answer might differ a little if the answer treats g as 10 instead of 9.81ms-2)

Explanation:

First, apply the formula Energy = Power x Time

Power -> 480W (given)

Time -> 12 seconds  (given)

Hence,

Energy = (480 x 12) J  (SI units of energy is in Joules, J)

            = 5760 J

Since Sarita lifts up the mass, the energy we have calculated above is gravitational potential energy.

That means 5760 J of gravitational potential energy.

Recall that another formula for gravitational potential energy (GPE) is

GPE = mgh (where h is the height lifted, mass is the mass and g is the gravitational constant of 9.81ms-2)

h = 10 metres (given)

Therefore,

5760 = m x 9.81 x 10  

98.1m = 5760

m = 58.71559g

Hence, mass lifted is 58.7g (in 3sf)

According to the given statement The time required is 2 seconds.

An unseen factor is an agent that has the power to alter the resting or moving condition of a body. It has a direction or a magnitude. The stress applied is the location at which force is applied, and the direction where the force applied is known also as direction of the force.

The vector composition of mass (m), acceleration, and the amount of force is used to express force (a). Mathematically, the equation or equation for force may be written as follows:

                             Force = mass x acceleration.

We know the force and the mass, so we can write:

6,000 N

= (1,200 kg) x (acceleration).    

      i.e. Acceleration = 6000N/1200kg = 5 m/s² .

That's the acceleration.  The speed changes by 5 m/s each second

that the force acts on it.  If the force pushes from behind, then it goes

5 m/s per second faster. It moves 5 m/s slower each second if the force is pushing from the front.

We wish to slow it down from its current speed of 10 m/s to 0 m/s. Therefore, the force must push from the front, and the task will be finished in (10/5) = 2 seconds.

So, time required is 2 seconds.

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Answer:

n = 4.25 x 10⁴ .

Explanation:

EMF required to be produced = 3 V .

Let n be the required no of turns .

rate of change of flux = n x B x A x f where n is no of turns of coil , B is magnetic field , A is area of coil and f is frequency of change .

B = .05 T , A = π x (.015)² = 7.065 x 10⁻⁴ m² , f = 2

emf induced = rate of change of flux

= n x  .05 T x 7.065 x 10⁻⁴ m² x 2

= .7065 x 10⁴ x n

Given

.7065 x 10⁻⁴ x n  = 3

n = 4.25 x 10⁴ .

4/3 m/s ( approximately 1.3333... m/s)

A pitcher throws a baseball towards a batter at 30m/s. The batter swings his bat and hits the baseball, then there is a transfer of energy in this situation : c) Yes, because the force from the bat changes the motion of the ball.

Although baseball may appear hard and solid, it actually behaves much like a rubber ball. In the fraction of a second that ball collides with the swinging bat, ball compresses as the energy of motion goes into deforming the ball and transforms it into an elastic potential energy.

The collision of baseball with bat is elastic and the collision between baseball and glove is nearly inelastic.

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Answer:

E = F * S       definition of energy

P = E / t = F * S / t         definition of power

P = 5.6E4 N * 4.5 m / 4.2 s = 60,000 watts

If an object is moving and the sum of all the vector forces on it is zero, then the object will move at a constant speed. The correct option is c.

A force's magnitude and direction are both represented by a force vector. This contrasts with expressing the force's magnitude alone, which is known as a scalar quantity.

Typically, a vector is represented by an arrow that points in the direction of the force and has a length proportionate to the strength of the force.

Therefore, the correct option is c, move at a constant speed.

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Answer:

[tex]\text{Using the formula: }v=\frac{d}{t}\\\therefore vt=d\\\text{Plug and chug:}46.2(8.66)=400.092\text{ metres}[/tex]

Answer: [tex]32.65\ m[/tex]

Explanation:

Given

mass of laptop m=2 kg

The velocity of car u=8 m/s

The coefficient of static friction is [tex]\mu_s=0.4[/tex]

The coefficient of kinetic friction is [tex]\mu_k=0.2[/tex]

As the car is moving, so the coefficient of kinetic friction comes into play

deceleration offered by friction [tex]\mu_kg=0.2\times 9.8\ m/s^2[/tex]

Using the equation of motion [tex]v^2-u^2=2as\\[/tex]

insert the values

[tex]0^2-8^2=2(-0.2\times 9.8)s\\\\s=\dfrac{64}{1.96}\\\\s=32.65\ m[/tex]

Explanation:

work a force is measured in newton-meters (N-m)

[tex] \huge \hookrightarrow \mathfrak{ \green{Answer}}[/tex]

we know,

[tex] \boxed{ \small{workdone = force \times displacement}}[/tex]

[tex]\longmapsto \: work \: done = N \times m[/tex]

[tex]work \: \: done \: \: is \: \: measured \: \: in \: \: \boxed {\color{gold}{Nm}}[/tex]

Nm = Newton meter

Answer:

800

Explanation:

10^2 = 100
8 x 100  = 800

A bar magnet's magnetic field lines flow from its north pole toward its south pole, just like they do in all magnets. Field lines that begin close to a pole's edges stay nearby the bar magnet longer than those that begin closer to the pole's centre.

Because the molecules in magnets are arranged so that their electrons spin in the same direction, magnets are unique. This configuration and motion produces a magnetic force that emanates from a north- and south-seeking pole, respectively.

At the poles, it is strongest.

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Answer: Visual acuity: sharpness of vision.

Myopia: nearsightedness

Refraction: bending of light rays.

Emmetropia: normal vision.

Accommodation: changes the shape of the eye lens to focus light on the retina.

Presbyopia: age-related farsightedness due to loss of elasticity in the lens.

Astigmatism: reduction in visual acuity due to changes in the cornea or lens.

Hyperopia: farsightedness

Myopia and hyperopia are refractive errors of the eye.

Presbyopia occurs in old age people.

Explanation:

Visual acuity: It can be defined as the inability to observe the details of shape of the object. Person loses sharpness in vision.

Myopia: It is a defect in vision in which person is able to observe the near by objects clearly but not able to see the distant objects.

Refraction: It can be defined as the bending of beam of light when it passes through from one substance to another.

Emmetropia: It is a vision without any defect.

Accommodation: It is the ability of the eye to adjust its focal length and adjusting the light on focus.

Presbyopia: It can be defined as the loss of ability of eye to focus on the object. It occurs in old age.

Astigmatism: It is a refractive error in which the eye does not focus light on retina.

Hyperopia: It is also called as farsightedness. Distant objects can be seen clearly but nearby appears blurry.

Answer:

b. a lens does not focus all colors of light to the same place.

Explanation:

Chromatic aberration is a defect of a lens. In this defect, the lens is unable to focus the different wavelengths of the light on a single focal point. It is also known as chromatic distortion and color fringing. It is caused by the dispersion of light while passing through a lens. As a result, the image might become blurred and different colors are observed around its edges. It can be corrected by the use of a combination of converging and diverging lenses.

Hence, the correct option will be:

b. a lens does not focus all colors of light to the same place.

Answer:

A. Q = 2.74 x 10⁷ J = 27.4 MJ

B. E = 3.91 x 10⁸ J = 391 MJ

Explanation:

A.

Heat rejected can be found as follows:

[tex]Q = mL[/tex]

where,

Q = Heat rejected = ?

m = mass = 82.1 kg

L = Latent Heat of fusion = 334000 J/kg

Therefore,

[tex]Q = (82.1\ kg)(334000\ J/kg)[/tex]

Q = 2.74 x 10⁷ J = 27.4 MJ

B.

First, we will calculate the efficiency of the Carnot Cycle as follows:

[tex]Efficiency = 1-\frac{T_1}{T_2}[/tex]

where,

T₁ = Heat intake temperature = 0°C + 273 = 273 k

T₂ = Heat rejection temperature = 20.6°C + 273 = 293.6 k

Therefore,

[tex]Efficiency = 1 - \frac{273\ k}{293.6\ k} \\\\Effciency = 0.07[/tex]

Therefore, the energy input required is:

[tex]Efficiency = \frac{Q}{E}\\\\E = \frac{Q}{Efficiency} = \frac{2.74\ x\ 10^7\ J}{0.07}[/tex]

E = 3.91 x 10⁸ J = 391 MJ

Answer:

Probably copper wire

Explanation:

I took the class and that's the only one that sounds right but I'm pretty dum lol