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Sum =X×(100)^3 /r^2(300+r) =620(100)^3/10^2(300+10) =20000

a. Frequency depends on amplitude of oscillation.

Even if it’s mass is doubled the time period will remain the same. As the increase in mass, the distance covered by the pendulum decreases.But the speed of the oscilating pendulum decreases resulting in no change in the time period.The answer is Option D.

In a circular motion under magnetic field, the centripetal force is provided by the magnetic force.

(mv2)/r = qvB

r = (mv)/(Bq)

T = (2Πr)/v

Putting r = (mv)/(Bq)

T = (2Πm)/(Bq)

Time period is independent of the velocity of charged particle.

Theperiodof a satellite is the time it takes it to make one full orbit around an object. The period of the Earth as it travels around the sun is one year. If you know the satellite’s speed and the radius at which it orbits, you can figure out its period.

1 answer is correct or not tell me

6/5 is correct answer

1 is the correct answer

1 is correct answer.

Hydropower plants capture the energy of falling water to generate electricity.

(c) is correct option

hydro power plant

acceleration will be 60-0/1=60m/sec^2and f=ma=5*60N

let the mass be M. and initial velocity be 0 ,now acceleration for first 0.2sec is F1/M = 25/M

so velocity after 0.2 is V = at = (25/M)*0.2 = 5/M

now the acceleration changes to -70/Mand, Vfinal = -5m/s = 5/M -70/M(0.1) => -5 = 1/M*(5-7)

=> M = 2/5 kg = 0.4kg

Integrate the equation of force with respect to 't'.Here upper limit will be 2 and lower will be 0. Final answer will be 4i+8j

50 gms water at 20 ⁰ C and 50 gms of water at 40⁰ C are mixed. Since the masses of the liquid at different temperatures are same, the answer is very easy and simple : average of 20⁰C and 40⁰C. that is: 30⁰C.=====================final temperature of the mixture = = [ m1 * T1 + m2 * T2 ] / (m1 + m2) = [ 50 gms * 20⁰ C + 50 gms * 40⁰C ] / (50+50)

= 3,000 / 100 = 30⁰C

====================another way using specific heats :

let the final temperature be = T ⁰C Amount of heat given out by the hot water = m * s * (40⁰C - T) = 50 gms * s* (40 -T) Amount of heat taken in by the cold water = m * s * (T - 20⁰C) = 50 gms * s * (T - 20 )

As the amounts are equal, because the heat is transferred from hotwater to the cold water without any loss of heat to any surroundings, 50 * s * (40 -T) = 50 gm * s * (T-20) 40 - T = T - 20 2 T = 60 => T = 30⁰C=============================

50 gms water at 20 ⁰ C and 50 gms of water at 40⁰ C are mixed. Since the masses of the liquid at different temperatures are same, the answer is very easy and simple : average of 20⁰C and 40⁰C. that is: 30⁰C.=====================final temperature of the mixture = = [ m1 * T1 + m2 * T2 ] / (m1 + m2) = [ 50 gms * 20⁰ C + 50 gms * 40⁰C ] / (50+50)

= 3,000 / 100 = 30⁰C

====================another way using specific heats :

let the final temperature be = T ⁰C Amount of heat given out by the hot water = m * s * (40⁰C - T) = 50 gms * s* (40 -T) Amount of heat taken in by the cold water = m * s * (T - 20⁰C) = 50 gms * s * (T - 20 )

As the amounts are equal, because the heat is transferred from hotwater to the cold water without any loss of heat to any surroundings, 50 * s * (40 -T) = 50 gm * s * (T-20) 40 - T = T - 20 2 T = 60 => T = 30⁰C

answer 643k-273=370 thek h..

answer 643 - 273=370

To find :The force required to increase the length of the wire by 0.2%Given: r=0.2mm : Y=9.0*10^10 N/m^2Formula used:Young's modulus = tensile stress/ tensile strainY= Force per unit area / strainSolution:Y=(F/A)/(∆L/L)

F=Y A (∆L/L)

F=Y (πr^2)(∆ L/L)

F=(9×10^10) ×3.14×(0.2×10^-3)^2 × ( 0.2/100)L/L

F=22.608NAnswer:22.608 N

Answer is a.acceleration must be positive for increase in speed. if acceleration is negative, it means the object is slowing down

Energy stored in a capacitor = cV²/2

Given

Capacitance = 20 mF = 20 x 10^3

Voltage V = 1000 v

Hence

energy = cV²/2

= 20 x 10^-3 x 1000^2 / 2

= 10^4 J

= 10 KJ

Hence the energy stored in the conductor will be 10 kilojoules.

(b) is correct option

Refrigeration may be defined as the process of achieving and maintaining a temperature below that of the surroundings, the aim being to cool some product or space to the required temperature.

Air conditioning is the process of altering the properties of air to more comfortable conditions, typically with the aim of distributing the conditioned air to an occupied space, such as a building or a vehicle, to improve the thermal comfort and indoor air quality

Solution :

Initial velocity=u=43.2km/hr =43.2 x 5/18 =12 m/sfinal velocity =V=0m/s [ As brakes are applied]Acceleration=a= -6.0m/s2Distance =s=?

Formula to be used : v²-u²=2as

s= v²-u²/2as=0²-12²/2x-6S=12m

Hence distance travelled before stopping is 12m

Avg speed = 7.5 + 7.5 / 2

it means = 7.5 km /h

D1 = 7.5×2/60= 0.25km

D2= 7.5×2/60= 0.25km

Total Distance= 0.25+0.25=0.50km

Total time taken = 2+2+56=60min= 1 HR

Average speed =total distance/ total timeAverage speed= 0.50/1= 0.50 km/hr

Decomposersand scavengers break down dead plants and animals. They also break down the waste (poop) of other organisms.

Decomposersare very important for anyecosystem. If they weren't in theecosystem, the plants would not get essential nutrients, and dead matter and waste would pile up.

Each DC machine can act as a generator or a motor. Hence, thisclassification is valid for both:DC generatorsandDC motors. DC machines are usuallyclassified on the basis of their field excitation method

1)Separately excited DC machines:In separately excited dc machines, the field winding is supplied from a separate power source. That means the field winding is electrically separated from the armature circuit.Separately excited DC generatorsare not commonly used because they are relatively expensive due to the requirement of an additional power source or circuitry. They are used in laboratories for research work, for accuratespeed control of DC motorswith Ward-Leonard system and in few other applications where self-excited DC generators are unsatisfactory. In this type, the stator field flux may also be provided with the help of permanent magnets (such as inpermanent magnet DC motors). PMDC (permanant magnet DC) motors are popularly used in small toys, e.g. a toy car.

2)Self-excited DC machines:In this type, field winding andarmature windingare interconnected in various ways to achieve a wide range of performance characteristics (for example, field winding in series or parallel with the armature winding).In aself-excited type of DC generator, the field winding is energized by the current produced by themselves. A small amount of flux is always present in the poles due to the residual magnetism. So, initially, current induces in the armature conductors of a dc generator only due to the residual magnetism. The field flux gradually increases as the induced current starts flowing through the field winding.

Wien’s law, also called Wien’s displacement law, relationship between the temperature of a blackbody (an ideal substance that emits and absorbs all frequencies of light) and the wavelength at which it emits the most light. It is named after German physicist Wilhelm Wien, who received the Nobel Prize for Physics in 1911 for discovering the law.

Wien studied the wavelength or frequency distribution of blackbody radiation in the 1890s. It was his idea to use as a good approximation for the ideal blackbody an oven with a small hole. Any radiation that enters the small hole is scattered and reflected from the inner walls of the oven so often that nearly all incoming radiation is absorbed and the chance of some of it finding its way out of the hole again can be made exceedingly small. The radiation coming out of this hole is then very close to the equilibrium blackbody electromagnetic radiation corresponding to the oven temperature. Wien found that the radiative energy dW per wavelength interval dλ has a maximum at a certain wavelength λm and that the maximum shifts to shorter wavelengths as the temperature T is increased. He found that the product λmT is an absolute constant: λmT = 0.2898 centimetre-degree Kelvin.

De Broglie wavelength is a wavelength, which is manifested in all the particles in quantum mechanics, according to wave-particle duality, and it determines the probability density of finding the object at a given point of the configuration space.

APN Junction Diodeis one of the simplest semiconductor devices around, and which has the characteristic of passing current in only one direction only. However, unlike a resistor, a diode does not behave linearly with respect to the applied voltage as the diode has an exponential current-voltage (I-V) relationship and therefore we can not described its operation by simply using an equation such as Ohm’s law.

If a suitable positive voltage (forward bias) is applied between the two ends of the PN junction, it can supply free electrons and holes with the extra energy they require to cross the junction as the width of the depletion layer around thePN junction is decreased.

By applying a negative voltage (reverse bias) results in the free charges being pulled away from the junction resulting in the depletion layer width being increased. This has the effect of increasing or decreasing the effective resistance of the junction itself allowing or blocking current flow through the diode.

L= h/p= h / mv , de-Broglei wave length for the electron.

L = h/ p = h/E/c= h/hf/c=c/f or E= hc/L for the photon

So h/p =hc/E

1/p= c/E

P=(2mKE)^1/2 for the electron.

So pE= C or E= c/ (2mKE)^1/2

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Light does not go away by leaking out through doors and windows. Light goes away by being quickly absorbed by materials and converted to heat and other forms of energy. In contrast to wind or smoke, light has no mass and is not composed of atoms. Because of this, light travels quickly in straight lines until it hits an object. It does not float around, billow with the wind, or leak out like a gas.

All of the light from a light bulb is converted to heat and other forms of energy within microseconds. Public Domain Image, source: Christopher S. Baird.When light hits an object, part of the light gets absorbed, part of it is transmitted trough the object, and part of it is reflected/scattered. Exactly how much gets absorbed, transmitted, or reflected depends on the material, shape, and thickness of the object. Thick metal objects like cooking pots reflect most of the light that hits them, absorb a little of the light, and transmit almost none of the light. In contrast, clear glass transmits most of the light, reflects a little of the light, and absorbs almost none. Coal absorbs most the light that hits it, and reflects and transmits almost none. Understanding and predicting exactly how much light of a certain color that a certain object absorbs, transmits, and scatters involves a complex field of study that involves many different effects not worth examining here. However, we can summarize the basic principles behind absorption.

A.Total Internal Reflection

signal communication works which principle " Refraction"

it works on refraction in optical fibre

refracton is answer of question ok

the complete reflection of a light ray reaching an interface with a less dense medium when the angle of incidence exceeds the critical angle.

it means the rays will come in the same medium????