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question_answer1) (a). If a force acts perpendicular to the Action of motion of a body, what is the amount of done? (b). A body is moving at constant speed over a frictionless surface. What is the work done by the weight?
question_answer2) The earth moving around the sun in a circular orbit is acted upon by a force and hence work must be done on the earth by the force. Do you agree by this statement?
question_answer3) A body is moving along a circular path. How much work is done by the centripetal force? Or Why is the work done by centripetal force zero?
question_answer4) A body of mass m is moving in a circle of radius r with a constant speed v. The force on the body is\[\frac{m{{\upsilon }^{2}}}{r}\] and is directed towards the centre. What is the work done by this force in moving the body over half the circumference of the circle?
question_answer5) Is it possible that a body be in accelerated motion under a force acting on the body, yet no work is being done by the force? Explain your answer giving a suitable example.
question_answer6) How much work is done by a coolie walking on a horizontal platform with a load on his head?
question_answer7) A porter moving vertically up the stairs with a suitcase on his head does work. Why?
question_answer8) Does the work done in raising a suitcase on to a platform depend upon how fast it is raised up?
question_answer9) In a tug of war one team is slowly giving way to the other. What work is being done and by whom?
question_answer10) A man rowing boat upstream is at rest with respect to the shore. Is he doing work?
question_answer11) Mountain roads rarely go straight up but wind up gradually. Why?
question_answer12) What sort of energy is associated with a bird flying in air?
question_answer13) When an arrow is shot, where from the arrow will acquire its kinetic energy?
question_answer14) Can a body have energy without momentum?
question_answer15) Can a body have momentum without energy?
question_answer16) A light body and a heavy body have the same momentum. Which one will have greater kinetic energy? Or Two bodies of unequal masses have same linear momentum, which one has greater kinetic energy?
question_answer17) A light body and a heavy body have the same kinetic energy. Which one will have the greater momentum?
question_answer18) How does the kinetic energy of a body change if its momentum is doubled?
question_answer19) Two bodies of masses \[{{m}_{1}}\] and \[{{m}_{2}}\] have the same linear momentum. What is the ratio of their kinetic energies?
question_answer20) Two bodies of masses \[{{m}_{1}}\] and \[{{m}_{2}}\] have equal kinetic energies. What is the ratio of their linear momenta?
question_answer21) Can there be a situation in which\[E-U<0\]?
question_answer22) Can the overall energy of a body be negative?
question_answer23) Does the potential energy of a spring decrease or increase when it is compressed or stretched?
question_answer24) If a block attached to a spring (whose other end is rigidly fixed) is pulled up to distance \[{{x}_{0}}\] and released, the amplitude of its motion cannot exceed \[\pm {{x}_{0}}\]. Why?
question_answer25) Springs A and B are identical except that A is stiffer than B, i.e., force constant \[{{k}_{A}}>{{k}_{B}}\]. In which spring is more work expended if they are stretched by the same amount?
question_answer26) Springs A and B are identical except that A is stiffer than B. In which spring is more work expended if they are stretched by the same force?
question_answer27) Which of the two: kilowatt hour or electron volt is a bigger unit of energy and by what factor?
question_answer28) Will water at the foot of the fall be at a different temperature from that at the top? If yes, explain.
question_answer29) Is it necessary that work done in the motion of a body over a closed loop is zero for every force in nature? Why?
question_answer30) When a constant force is applied to a body moving with constant acceleration, is the power of the force constant? If not, how would force have to vary with speed for power to be constant?
question_answer31) What are central forces? Are they conservative in nature?
question_answer32) When is the exchange of energy maximum during an elastic collision?
question_answer33) Is whole of the kinetic energy lost in any perfectly inelastic collision?
question_answer34) Can you associate potential energy with a non-conservative force?
question_answer35) Two bodies moving towards each other collide and move away in opposite directions. There is some rise of temperature of the bodies in the process. Explain the reason for the rise of temperature and state what type of collision is it.
question_answer36) A spark is produced, when two stones are struck against each other. Why?
question_answer37) A lorry and a car with the same kinetic energy are brought to rest by the application of the brakes which provide equal retarding force. Which of them will come to rest in a shorter distance?
question_answer38) A truck and a car are moving with the same kinetic energy on a straight road. Their engines are simultaneously switched off. Which one will stop at a lesser distance?
question_answer39) A rocket explodes in mid air. How does this affect (a) its total momentum and (b) its total kinetic energy?
question_answer40) The velocity of an aeroplane is doubled. (a) What will happen to its momentum? Will the momentum remain conserved? (b) What will happen to its K.E.? Will the energy remain conserved?
question_answer41) A uniform rectangular parallelopiped of mass m having sides \[l\], \[2l\] and \[4l\] is placed in turn on each of its three sides on a horizontal surface. What is the potential energy of the parallelopiped in each of these positions? Which position will be the most stable?
question_answer42) What happens to the potential energy when (a) two protons are brought close together (b) one proton and one electron are brought close together?
question_answer43) A particle is moving in a circular path of a given radius with number of rotations per second (i) constant, (ii) increasing, (iii) decreasing. What happens to work done in the three cases?
question_answer44) "Chemical, gravitational and nuclear energies are nothing but potential energies for different types of forces in nature." Explain the statement clearly with examples.
question_answer45) In a thermal power station, coal is used for the generation of electricity. Mention how energy changes from one form to another before it is transformed into electrical energy?
question_answer46) Explain how fast moving neutrons can be quickly slowed down by passing through, water or heavy water.
question_answer47) Two ball bearings of mass m each moving in the opposite directions with equal speed \[\upsilon \] collide head on with each other. Predict the outcome of the collision, assuming it to be perfectly elastic.
question_answer48) A body of mass m moving with speed \[\upsilon \]collides elastically head-on with another body of mass m initially at rest. Show that the moving body will come to a stop as a result of this collision.
question_answer49) A uniform chain of length L and mass M is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If g is acceleration due to gravity, calculate work required to pull the hanging part on the chain.
question_answer50) A body of mass M is moved along a straight line by a machine delivering a constant power P. Find the expression for the distance moved by the body in terms of M, P and t.
question_answer51) Why a metal ball rebounds better than a rubber ball?
question_answer52) Explain, throwing mud on a wall is an example of perfectly inelastic collision.
question_answer53) Nuclear fission and fusion reactions are examples of conversion of mass into energy. Can we say that strictly speaking, mass is converted into energy even in an exothermic chemical reaction?
question_answer54) The energy released in fusion reaction of light nuclei is much less than the energy released in a fission reaction of a heavy nucleus. Why is then a hydrogen bomb (based on nuclear fusion) far more powerful than an atomic bomb (based on nuclear fission)?
question_answer55) What is the minimum amount of energy released in the annihilation of an electron-positron pair?
question_answer56) By convention, the forces which fall off to zero at large distances, the potential energy at infinity is taken to be zero. With this choice, is the potential energy positive for (a) electron-positron bound state (b) planet- satellite system and (c) electron-electron system?
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