9th Class Science Work and energy Question Bank

done Work Power and Energy HOTS Subjective Problems Total Questions - 25

• question_answer1)
  A force of 5 N acting on a body at an angle of\[\text{3}0{}^\circ \]with horizontal direction displaces it horizontally through a distance of 6 m. Calculate the work done.
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• question_answer2)
  A body of mass 10 kg is falling freely from a height of 2 m. What is the loss of PE as it reaches the ground. (Take\[\text{g}=\text{9}.\text{7 m}/{{\text{s}}^{\text{2}}}\]).
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• question_answer3)
  A body of mass 3 kg is pulled up along an incline through a vertical height of 2 m. The work done is ?????
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• question_answer4)
  A person of mass 50 kg carries a case of 10 kg to the upstairs at a vertical height of 4 m. The work done is ?????
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• question_answer5)
  The work done by a person in carrying a box of mass 15 kg through a vertical height of 5 m is 4900J.The mass of the person is ?????
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• question_answer6)
  A tank of size\[\text{1m}\times \text{2m}\times \text{2m}\] is to be filled with water lifting from a well of average depth 5m. Find the work done.
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• question_answer7)
  A cylindrical barrel is buried vertically in ground with its opening at the ground level. The area of cross-section of the barrel is\[\text{1 }{{\text{m}}^{\text{2}}}\]. The depth of a barrel is 1.5 m. It is full of water. Find the work done in bailing out the water.
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• question_answer8)
  Find the power of the engine deployed to lift water at the rate of 5 litre of water in one second through an average height of 10 m from a well of depth 10 m. Assume 10% of power of engine is wasted.
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• question_answer9)
  Find the horse power of engine used to fill a tank of size\[\text{1m}\times \text{2m}\times \text{1m}\] situated at an average height of 20 m with water from a well of depth 17. 3 m in 5 minutes. Assume 20% power is wasted.
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• question_answer10)
  A train having 50 wagons of 25 ton each is moving with uniform velocity of 54 kmph. Find the horse power developed, if the average frictional force acting is 10 N per ton.
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• question_answer11)
  A car of mass 1 ton moving with a velocity of 90 kmph is brought to rest in 20 S. What is the brake power?
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• question_answer12)
  A person of mass 60 kg finished the long jump at a distance of 9m Considering the person moves along the parabolic path and angle of jump to be\[\text{45}{}^\circ \], calculate the initial K.E.
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• question_answer13)
  A body of weight 30 N falls freely from a height of 15 m and buries into sand through a distance of 0.5 m. Find the resistance due to sand.
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• question_answer14)
  A motor having an efficiency 80%, penetrates a crane having an efficiency of 40 %. What is the constant speed with which the crane lifts a body of mass 100 kg, if motor used is of 5 H.P.
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• question_answer15)
  A fire hose is uncoiled by pulling the end of the hose horizontally at a uniform speed of 2.2 m/s. If the linear density of the hose is \[0.2\text{ }kg{{m}^{-1}},\] find the work done in uncoiling the 20 m hose.
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• question_answer16)
  A body falling from a height of 10 m rebounds from a hard floor. If it loses 20% of its energy in impact, what is the height to which it rises?
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• question_answer17)
  A person of mass 42 kg eats bananas of 980 cal. If this energy is used up to lift him from the ground, the height to which he can climb is ???.
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• question_answer18)
  A body of mass 2 kg is thrown up vertically with a kinetic energy of 490 J. If the acceleration due to gravity is \[\text{9}.\text{8 m}/{{\text{s}}^{\text{2}}}\], the height at which the KE of the body becomes half of the original value is ?????
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• question_answer19)
  A particle of mass 4 m which is at rest explodes into three fragments. Two of the fragments each of mass 'm' are found to move with a speed of 'v' each in mutually perpendicular directions. The total energy released in this process is ??..
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• question_answer20)
  If the momentum of a body is doubled, what happens to its kinetic energy?
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• question_answer21)
  If the momentum of a body is made\[\frac{1}{n}\]times, the kinetic energy becomes ???? times the original.
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• question_answer22)
  If the kinetic energy is doubled, the momentum becomes ???? times.
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• question_answer23)
  A car and a truck are moving with same momentum. If they are stopped by same retarding force, then (i) Which one will travel greater distance before coming to rest? (ii) Which one will take greater time to come to rest?
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• question_answer24)
  A car and a truck are moving with same kinetic energies. If they are stopped by same retarding force, then (i) Which one will travel more distance before coming to rest? (ii) Which one will take more time to come to rest?
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• question_answer25)
  A bullet of mass m fired into a stationary large wooden block with velocity v penetrates a distance\[x\]before coming to rest. What is the resistance provided by the wooden block.
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