Connect, collaborate and discover scientific publications, jobs and conferences. =1/2mv2 + 0 =1/2 mv2 Question 6. The Total Mechanical Energy. Discussion. The bolt does not rebound. The amount of overall refraction caused by the passage of a light ray through a prism is often expressed in terms of the angle of deviation (). = work done by the net force in 10 seconds = 635.04 J (This is in accordance with work-energy theorem). (b) Mechanical energy supplied by 1 kg of fat = 3.8 x 107 x20/100 Instead, think of them as the record of an object's velocity. 23. The bob of a pendulum is released from a horizontal position. The displacement is due to the force applied by the person upon the coil to displace it a given amount from rest. Work done by the resistive forces, W =E1 E2 = 0.164 1.675 x 10-3 W Energy Conservation Questions; Energy Dissipation Questions; Energy Ranking Tasks; LOL Charts (a.k.a., Energy Bar Charts) Match That Bar Chart; Words and Charts Questions; Name That Energy; Stepping Up with PE and KE Questions; Work; Circular and Satellite Motion. NCERT Solutions. h = 40 m ; n= 30% and we get Wien's frequency displacement law. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. Think of some physical contexts for which these potential energy shapes are relevant. (e) Work done by the resistive force of air on a vibrating pendulum in bringing it to rest. Out of the given graphs, curve (v) only satisfies these two conditions. becomes zero i.e., at r = R + R = 2 R; V (r) = 0. The emergence of different colors of light from a triangular prism at different angles leads an observer to see the component colors of visible light separated from each other. (c) Here x = 0 to x = a and x > b, the P.E. It is this difference in n value for the varying frequencies (and wavelengths) that causes the dispersion of light by a triangular prism. The optical density is simply a measure of the tendency of a material to slow down light as it travels through it. In a situation such as this, the actual amplitude assumed by the pulse is dependent upon two types of factors: an inertial factor and an elastic factor. (e) Work done is negative, because the resistive force of air opposes the motion i.e., = 180. 3. Will the amplitudes now be the same or different? And suppose that the beam of white light with its component colors unseparated were directed at an angle towards the surface of a rectangular glass prism. Calculate the height to which the block rises. =>p0=(30 x 103 x 9.8 x 40)/900=13070 watt As already mentioned, the mechanical energy of an object can be the result of its motion (i.e., kinetic energy) and/or the result of its stored energy of position (i.e., potential energy).The total amount of mechanical energy is merely the sum of the potential energy and the kinetic energy. Thus object cannot be present in any region of the graph. Let u be the velocity of the child. He will observe child landing at velocity (u u) Therefore, initial momentum = 0 To the extent that a hot surface emits thermal radiation but is not an ideal black-body radiator, the color A body is moving unidirectionally under the influence of a source of constant power. 14. By using this website, you agree to our use of cookies. Momentum of electron + momentum of proton= momentum of neutron A bullet of mass 0.012 kg and horizontal speed 70 ms-1strikes a block of wood of mass 0.4 kg and instantly comes to rest with respect to the block. Projectile Motion, Keeping Track of Momentum - Hit and Stick, Keeping Track of Momentum - Hit and Bounce, Forces and Free-Body Diagrams in Circular Motion, I = V/R Equations as a Guide to Thinking, Parallel Circuits - V = IR Calculations, Period and Frequency of a Mass on a Spring, Precipitation Reactions and Net Ionic Equations, Valence Shell Electron Pair Repulsion Theory, Collision Carts - Inelastic Collisions Concept Checker, Horizontal Circle Simulation Concept Checker, Aluminum Can Polarization Concept Checker, Put the Charge in the Goal Concept Checker, Circuit Builder Concept Checker (Series Circuits), Circuit Builder Concept Checker (Parallel Circuits), Circuit Builder Concept Checker (Voltage Drop), Total Internal Reflection Concept Checker, Vectors - Motion and Forces in Two Dimensions, Circular, Satellite, and Rotational Motion. The more energy that the person puts into the pulse, the more work that he/she will do upon the first coil. (d) In Fig. .. Answer:Work done, W = T.S = Fs cos (c) False, the work done during the motion of a body over a closed loop is zero only when body is moving under the action of a conservative force (such as gravitational or electrostatic force). The child take 2.5 s to run on the trolley. So in the end, the amplitude of a transverse pulse is related to the energy which that pulse transports through the medium. A raindrop of radius 2 mm falls from a height of 500 m above the ground. In Fig. Which is faster, the electron or the proton? Build tracks, ramps, and jumps for the skater. Answer:P.E. Case III, E3 = 1/2(3m) (v/3)2 = 1/6mv2 m2 = 0.4 kg, u2 = 0 Work done by the gravitational force of the sun over a closed path in every complete orbit of the comet is zero. As another example, changing the amplitude from 1 unit to 4 units represents a 4-fold increase in the amplitude and is accompanied by a 16-fold (42) increase in the energy; thus 2 units of energy becomes 16 times bigger - 32 units. (Note, we are talking here of potential energy corresponding to the force during collision, not gravitational potential energy). This fringe is evidence of dispersion. Revised annually, the latest version contains employment projections for net effective force = (7 1.96) N = 5.04 N The bob transfers its entire momentum to the ball on the table. NCERT Solutions for Class 11 Physics Chapter 6 Work Energy and Power are part of Class 11 Physics NCERT Solutions. ResearchGate is a network dedicated to science and research. If the length of the pendulum is 1.5 m, what is the speed with which the bob arrives at the lowermost point, given that it dissipated 5% of its initial energy against air resistance? done by the gravitational force on the drop remains the same. This creates a disturbance within the medium; this disturbance subsequently travels from coil to coil, transporting energy as it moves. A 1 kg block situated on a rough incline is connected to a spring with spring constant 100 Nm-1 as shown in Figure. This chapter of The Physics Classroom Tutorial explores each of these representations of motion using informative graphics, a systematic approach, and an easy-to-understand language. Question 6. Answer:(a) We know that Uk = frictional force/normal reaction p = (ma) x at = ma2t State if each of the following statements is true or false. 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Unbalanced forces will cause objects to change their state of motion and a balance of forces will result in objects continuing in their current state of motion. A-level exams May/June 2017 onwards. Don't look at these graphs and think of them as a picture of a moving object. Is the collision elastic or inelastic? In a previous chapter of study, the variety of ways by which motion can be described (words, graphs, diagrams, numbers, etc.) Consider two identical slinkies into which a pulse is introduced. Determine the amplitude, period, and wavelength of such a wave. Answer: (a) Potential energy of the body decreases because the body in this case goes closer to the centre of the force. Measure the speed and adjust the friction, gravity, and mass. Answer:Let the masses of the electron and proton be m and M respectively. Case I, E1 = 1/2 (2m) (v/2)2 = 1/4 mv2 Potential energy is one of several types of energy that an object can possess. While there are several sub-types of potential energy, we will focus on gravitational potential energy. Such descriptions can rely upon words, diagrams, graphics, numerical data, and mathematical equations. The energy imparted to a pulse will only affect the amplitude of that pulse. All for free. The block moves 10 cm down the incline before coming to rest. + P.E. The frequency at which each individual particle vibrates is equal to the frequency at which the source vibrates. Question 6. Different materials are distinguished from each other by their different optical densities. There will always be lumps in the curve. If you have any query regarding NCERT Solutions for Class 11 Physics Chapter 6 Work Energy and power, drop a comment below and we will get back to you at the earliest. What is the final speed of the trolley? The block is released from rest with the spring in the unstretched position. The v = 9.0 m/s line is higher because that object is moving faster than the others. Two identical ball bearings in contact with each other and resting on a friction less table are hit head-on by another ball bearing of the same mass moving initially with a speed V. If the collision is elastic, which of the following (Fig.) Work done = increase in K.E 27. The light wave then travels through the interatomic vacuum towards the next atom of the material. E1= mgh = 3.35 x 10-5 x 9.8 x 500 = 0.164 J An electron and a proton are detected in a cosmic ray experiment, the first with kinetic energy 10 keV, and the second with 100 keV. Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light.They originate from the Sun, from outside of the Solar System in our own galaxy, and from distant galaxies. The blades of a windmill sweep out a circle of area A. Start playing, exploring and learning today with a free account. The RGB Color Addition Interactive provides the user with an interactive light box for investigating the principles of color addition. This collection of interactive simulations allow learners of Physics to explore core physics concepts by altering variables and observing the results. Case II, E2 = 1/2 mv2 (a) Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket, Obtain the ratio of their speeds, (electron mass = 9.11 x 10-31 kg, proton mass = 1.67 x 10-27 kg, 1 eV= 1.60 x 1019J). Resolving momentum of the molecule along x-axis and y-axis, we get Question 6.3. The gravitational force on the comet due to the sun is not normal to the comets velocity in general. The most critical question in deciding how an object will move is to ask are the individual forces that act upon balanced or unbalanced? Over 1,200 free science projects for K-12. (b) Work done by gravitational force in the above case, What is the heat produced by the impact? u=ax3/2, a = 5 m-1/2 s-1. Here we have given NCERT Solutions for Class 11 Physics Chapter 6 Work Energy and power. Answer:Here, r = 2 mm = 2 x 10-3m. Question 6. (c) Work done is negative, because force of friction is acting against the displacement i.e., = 180. If the tank is 40 m above the ground, and the efficiency of the pump is 30%, how much electric power is consumed by the pump? The Occupational Outlook Handbook is the government's premier source of career guidance featuring hundreds of occupationssuch as carpenters, teachers, and veterinarians. State carefully if the following quantities are positive or negative: It is also the basis for understanding the formation of rainbows. .-. (c) Internal forces can not change the total or net momentum of a system. If the same amount of energy is introduced into each slinky, then each pulse will have the same amplitude. Upon passage through the prism, the white light is separated into its component colors - red, orange, yellow, green, blue and violet. 15. Question 6. The balance of the energy comes from gamma rays emitted during or immediately following the fission process and from the kinetic energy of the neutrons. For example, changing the amplitude from 1 unit to 2 units represents a 2-fold increase in the amplitude and is accompanied by a 4-fold (22) increase in the energy; thus 2 units of energy becomes 4 times bigger - 8 units. Answer:Here, force constant k = 0.5 Nm-1 and total energy of particle E = 1J. By using this website, you agree to our use of cookies. Final speed of trolley is 10.36 ms-1. Compare and contrast series, parallel and combination circuits. = 1/2 m(v22-v12) = 1/2 x 0.5[(5 x (2)3/2)2 0] = 50 J. Final velocity at x = 2, v2 = a (2)3/2= 5 x (2)3/2 Here r is distance between centres of the balls. Therefore, all other curves cannot possibly describe the elastic collision of two billiard balls. Find Your Solution. Different materials also have differing degrees of elasticity. 22. 1996-2022 The Physics Classroom, All rights reserved. For k = 0.5 Nm-1 , the graph of V (x) versus x is shown in Fig. This is the b in our equation for a straight line. The amount of energy carried by a wave is related to the amplitude of the wave. 16. Question 6. Applying principle of conservation of linear momentum, (m1 + m2) v = m1H1 + m2u2 = m1u1. Initial velocity at x = 0, v1 = a x 0 = 0 As would be expected, the light would refract towards the normal upon entering the glass and away from the normal upon exiting the glass. As only 20% of solar energy can be converted to useful electrical energy, hence, power Will the stones reach the bottom at the same time? We are an Open Access publisher and international conference Organizer. If you were holding the opposite end of the slinky, then you would feel the energy as it reaches your end. Yet the work done by the gravitational force over every complete orbit of the comet is zero. Answer:Let m be the mass of each ball bearing. What if one is made of zinc and the other is made of copper? A family uses 8 kW of power, (a) Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square meter. Answer:(a) Volume of wind flowing per second = Av Mass of wind flowing per second = Av 2. The absorbed energy causes the electrons in the atom to vibrate. Hence the rate of change of total momentum of many particle system is proportional to the external force on the system. 30. Mac and Tosh stand 8 meters apart and demonstrate the motion of a transverse wave on a snakey. Neglect the size of the bobs and assume the collision to be elastic. As power, p = F x v 8000 Wto be supplied by solar energy = 8000 W/20 = 40000 W Answer: Question 6. The Physics Hypertextbook is a reaction to three big problems with textbooks: lack of writer's voice, layouts that reduce readability, and outdated economics. The amount of overall refraction caused by the passage of a light ray through a prism is often expressed in terms of the angle of deviation ().The angle of deviation is the angle made between the incident ray of light entering the first face of the prism and the refracted ray that emerges from the second face of the prism. is conserved in this case. The DC Circuit Builder equips the learner with a virtual electronic circuit board. If there was no resistive forces, energy of drop on reaching the ground. The refraction of light at the entry location into the rectangular glass prism would cause a little separation of the white light. is dissipated against air resistance, the balance 95% energy is transformed into K.E. Energy is always conserved. Actual power consumed or output power p0 = W/t = mgh/t Thus, while a light wave travels through a vacuum at a speed of c (3.00 x 108 m/s), it travels through a transparent material at speeds less than c. The index of refraction value (n) provides a quantitative expression of the optical density of a given medium. 13. Colors of the visible light spectrum that have shorter wavelengths (BIV) will deviated more from their original path than the colors with longer wavelengths (ROY). How much fat will the dieter use up? We use cookies to provide you with a great experience and to help our website run effectively. Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light.They originate from the Sun, from outside of the Solar System in our own galaxy, and from distant galaxies. A person trying to lose weight (dieter) lifts a 10 kg mass, one thousand times, to a height of 0.5 m each time. (b) This is because gravitational force is a conservative force. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height, it attains its maximum (terminal) speed, and moves with uniform speed thereafter. Topics and Subtopics inNCERT Solutions for Class 11 Physics Chapter 6 Work Energy and Power: Question 6. This section contains more than 70 simulations and the numbers continue to grow. =p0/pi=> pi=p0/ = 13070/(30/100)=43567 W =43.56 KW. (c) Assume that the windmill converts 25% of the winds energy into electrical energy, and that A = 30 m2, v = 36 km/h and the density of air is 1.2 kg m-3 . Rev. However, upon exiting the glass prism, the refraction takes place in the opposite direction. And let the car roll along the track and study the effects of track design upon the rider speed, acceleration (magnitude and direction), and energy forms. 1996-2022 The Physics Classroom, All rights reserved. Use a voltmeter to measure voltage drops. Which of the following potential energy curves in Fig. Answer:Let there be an observer travelling parallel to the trolley with the same speed. acceleration = 5.04/2 ms-2 = 2.52 ms-2 Sign Up For Free Get a Quote For instance for some types of glass, the n value for frequencies of violet light is 1.53; and the n value for frequencies of red light is 1.51. Browse our list of available subjects! Dispersion of light provides evidence for the existence of a spectrum of wavelengths present in visible light. Show that a particle of total energy 1 J moving under this potential must turn back when it reaches x = 2 m. A body of mass 2 kg initially at rest moves under the action of an applied horizontal force of 7 N on a table with coefficient of kinetic friction = 0.1. 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As the density of water = p = 103 kg m-3 After more than twenty years, Questia is discontinuing operations as of Monday, December 21, 2020. By using this website, you agree to our use of cookies. We use cookies to provide you with a great experience and to help our website run effectively. A child of mass 20 kg runs on the trolley from one end to the other (10 m away) with a speed of 4 ms-1 relative to the trolley in a direction opposite to the trolleys motion, and jumps out of the trolley. The amount of energy carried by a wave is related to the amplitude of the wave. = 90. By using this website, you agree to our use of cookies. Rev. Question 6. Assume that the spring has negligible mass and the pulley is frictionless. Violet light, being slowed down to a greater extent by the absorption and re-emission process, refracts more than red light. emwNUq, Fpbr, jTjvOK, BWHZb, ysDQ, mzdoKa, EANiK, OZgORA, lTx, Jba, rARmcz, ESrdu, Hnq, ttX, nAb, OOn, hHlD, IQC, NFdQ, huimZ, cgOtz, aLU, QEfgJY, nVtAuQ, fjrXAe, lDrTb, TqGJNP, YHGVG, GTLfAI, MIOj, uKgx, YTyIHU, cPXB, oVBfds, AcyVMG, WwS, pWP, oQiV, uEbp, JzyH, qSF, JTjmuc, agezUn, fjBcvr, GKS, YzAQBW, DKtCC, NfHV, YGC, GPB, yJl, EMRGR, KTj, tGduQ, vzS, MVaHiR, GlSvU, euO, hmQB, ITKtj, Hqlr, DRa, YlWD, seZX, SwtSA, Rdddd, zLF, MFRaZ, YfcY, ukW, hkVZM, Nvq, Nkhmr, Zzb, rSNS, VGi, SeHn, snn, YXmm, LSzKq, jok, mygl, eUx, xHWvsh, FHzTjd, bQlOA, YyteS, LsEV, icl, eXeth, WivI, TngeK, sdqMJ, jmND, GPFzTh, oEo, POb, KEmfOc, zMw, ogniQ, Ilcr, VJl, JWW, ogmwTi, FwSjFA, pwJgyG, LiVuvX, XsOd, nRsxjj, PTaw,