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question_answer1) What is the work done by the nucleus for the electron to revolve in its orbit?
question_answer2) Can a body have zero work done, when it is accelerated under the action of a force?
question_answer3) Does the work done in raising a body to a height, depend on how fast it is raised? Justify.
question_answer4) What is the work done by a satellite, while it revolves round the earth in circular orbit?
question_answer5) During a tug of war, team A pulls on team B by applying a force of 1100 N, to the rope between them. How much to the rope between them. How much work does team A do, if they pull team B towards them, by a distance of 2.0 m?
question_answer6) Find the work done by a person in carrying a box weighing 30 kg over his head, when he travels a distance of 20m (i) on a plane ground (ii) vertically up (\[\text{g}=\text{9}.\text{8 m}{{\text{s}}^{-\text{2}}}\])
question_answer7) Find the work done in lifting 4 cement bags, each of mass 50 kg to the top of a building of height 20 m.
question_answer8) A massive box is dragged along a horizontal floor by a rope. The rope makes an angle of \[\text{6}0{}^\circ \] with the horizontal. Then, find the amount of work done.
question_answer9) A ball of mass 1 kg thrown upwards, reaches a maximum height of 5 m. Calculate the work done by the force of gravity during this vertical displacement.
question_answer10) If the work done by a force in moving an object through a distance of 20m is 24.2J, then what is the magnitude of the force?
question_answer11) A boy of mass 70 kg, run up a flight of 50 stairs, each measunng 0.20 m in 20 s. Calculate, (i) Force acting on the body (ii) Work done by the body (\[\text{g}=\text{1}0\text{m}{{\text{s}}^{-\text{2}}}\])
question_answer12) What should be the mass of a man if he has to do 2500 joules of work in climbing a tree 5 m tall? (\[\text{g}=\text{9}.\text{8 m}/{{\text{s}}^{\text{2}}}\])
question_answer13) A drop of water of volume\[\text{5}\times \text{1}{{0}^{-\text{8}}}\text{ }{{\text{m}}^{\text{3}}}\] falls from a height of 100m. If \[\text{g}=\text{1}0\text{m}/{{\text{s}}^{\text{2}}}\], what is the work done by the gravitational force? (density of water is\[\text{1}{{0}^{\text{3}}}\text{ kg}/{{\text{m}}^{\text{3}}}\])
question_answer14) A body of mass 0.5 kg is moving with a constant velocity of 2 m/s. In order to bring it to rest in a distance of 2m, find the work done.
question_answer15) A force acts on a body along its direction of motion. The graph given, show the relation between force and displacement. Find the work done by the force.
question_answer16) If a young man does 500 J of work in 5 s and old man does the same work in 10 s. Who has more power, young man or the old man?
question_answer17) A 1 Kilowatt motor is used to pump up water through a height of 10 m. Calculate the amount of water lifted per minute.
question_answer18) A man weighing 500 N carries a load of 100 N up a flight of stairs 4 m in 5 seconds. What is the power?
question_answer19) Find the power of an electric motor, if it lifts 200 kgf of water in 5 minutes, from a well of 120m depth.
question_answer20) A person weighting 60 kg goes upto the top of a 10 m high building in 40s. Find the power.
question_answer21) What will be the potential energy of a body of mass 1 kg kept at a height of 5 m. (Take \[\text{g}=\text{1}0\text{m}{{\text{s}}^{-\text{2}}}\])
question_answer22) To what height should a box of mass 150 kg be lifted, so that its potential energy may become 7350 joules? (\[\text{g}=\text{9}.\text{8 m}/{{\text{s}}^{\text{2}}}\])
question_answer23) A body of mass 2 kg is thrown vertically upwards with an initial velocity of 20 m/s. What will be its potential energy at the end of 2 s? (\[\text{g}=\text{1}0\text{ m}/{{\text{s}}^{\text{2}}}\])
question_answer24) A boy weighing 50 kg climbs up a vertical height of 100 m. Calculate the amount of work done by him. How much potential energy does he gain?
question_answer25) A body is moving from A which is at a height of 25 m from the ground and follows the path as shown in the figure. Find the velocity of the body on reaching 'B' which is at a height of 5 m from the ground.
question_answer26) A body of mass 5 kg starting from point 'A' which is it at a height of 5m from the ground, follows the path ABC as shown in the figure and comes to rest on reaching C, which is at a height of 3m from the ground. If the length of the path ABC is 40m, find the resistance force that makes the body stop at C.
question_answer27) A vehicle is moving with a velocity of 80 kmph. Calculate its kinetic energy, if the mass of the vehicle is 1000 kg.
question_answer28) A body of mass 1 kg is allowed to fall freely under gravity. Find the K.E. of the body, 5 sec after it starts falling. (Take\[\text{g}=\text{1}0\text{m}{{\text{s}}^{-\text{2}}}\])
question_answer29) A body mass 4 kg is moving with a speed of \[\text{1}0\text{ m}{{\text{s}}^{-\text{1}}}\] Find its kinetic energy.
question_answer30) A moving body of mass 10 kg has 20 Joules of kinetic energy. Calculate its speed.
question_answer31) A man drops a 10 kg rock from hte top of a 5m ladder. What is its K.E., when it reaches the ground? (Take \[\text{g}=\text{1}0\text{m}{{\text{s}}^{-\text{2}}}\])
question_answer32) Two bodies of equal masses move with uniform velocity v and 2v respectively. Find the ratio of their kinetic energies.
question_answer33) Find the momentum of the body of mass 100 g having a kinetic energy of 20J?
question_answer34) How fast should a man of mass 50 kg run, so that his kinetic energy be 625 J?
question_answer35) A horse and a dog are running with the same speed. If the mass of the horse is ten times that of the dog, then what is the ratio of their kinetic energies?
question_answer36) Two objects having equal masses are moving with uniform velocities of 2 m/s and 6 m/s respectively. Calculate the ratio of their kinetic energies?
question_answer37) If the speed of a vehicle increases by 2 m/s, its kinetic energy is doubled. What was the original speed of the vehicle?
question_answer38) A body moving at 2 m/s can be stopped over a distance x. If the kinetic energy of the body is doubled, how long will it go before coming to rest, if the retarding force remains unchanged?
question_answer39) The percentage increase in kinetic energy when velocity of the body is doubled is ____.
question_answer40) What happens to kinetic energy of a body when 1/4 mass is removed and the velocity is doubled?
question_answer41) A bullet strikes a wooden plank with a velocity of 54 kmph and emerges from it with a velocity of 36 kmph. If the thickness of the plank is 20cm, find the average resistance (in Newton) offered by it to the motion of the bullet. What is the thickness of the same plank that would have just stopped the bullet? Mass of the bullet = 15 gm.
question_answer42) A boy weighing 40 kg makes a high jump of 1.5 m. (i) What is his kinetic energy at the highest point?' (ii) What is his potential energy at the highest point?
question_answer43) What kind of energy transformation takes place at a hydroelectric power station?
question_answer44) Which device converts chemical energy into electrical energy?
question_answer45) When an arrow is released from a stretched bow and arrow, the arrow moves in air. What is the source of the energy of the arrow? Explain.
question_answer46) The head of a nail becomes warm when it hammered into a wall. Why?
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