9th Class Science Work and energy Question Bank

done Work, Energy and Sound Total Questions - 40

• question_answer1)
  Which of the following is the S.I. unit of force?
  A)
  Newton              done clear
  B)
  Meter done clear
  C)
  Joule     done clear
  D)
         Ampere done clear
  E)
  None of these done clear
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• question_answer2)
  A ball weighing \[\frac{1}{2}\] kg has a kinetic energy 1 joule when its speed is:
  A)
  1 m/s                done clear
  B)
  2 m/s done clear
  C)
  3 m/s    done clear
  D)
         4 m/s done clear
  E)
  None of these done clear
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• question_answer3)
  What kind of energy is present in a rotating wheel?
  A)
  Kinetic energy done clear
  B)
         Electrical energy done clear
  C)
  Potential energy done clear
  D)
         Wind energy done clear
  E)
  None of these done clear
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• question_answer4)
  An object of 10 kg moves with a uniform velocity of 2 m/s, what is the kinetic energy possessed by the object?
  A)
  20 J                  done clear
  B)
  10 J done clear
  C)
  40 J                  done clear
  D)
         30 J done clear
  E)
  None of these done clear
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• question_answer5)
  A person lifts a luggage of 10 kg at the height of 2 m above the ground. What is the potential energy possessed by the luggage?
  A)
  180 J                done clear
  B)
  196 J done clear
  C)
  20 J                  done clear
  D)
         10 J done clear
  E)
  None of these done clear
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• question_answer6)
  What is the S.I. unit of power?
  A)
  Joule                 done clear
  B)
  Newton done clear
  C)
  Newton meter done clear
  D)
         Watt done clear
  E)
  None of these done clear
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• question_answer7)
  An object is dropped from certain height. Which of the following statements is correct about the object when it is about to reach the ground?
  A)
  It has minimum kinetic energy. done clear
  B)
  It has maximum kinetic energy. done clear
  C)
  The kinetic energy is zero at this point. done clear
  D)
  It has maximum potential energy. done clear
  E)
  None of these done clear
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• question_answer8)
  Law of conservation of energy states that_____.
  A)
  Total energy of system remains constant. done clear
  B)
  Energy cannot be created or destroyed. done clear
  C)
  There is no gain or loss of energy in a system. done clear
  D)
  All the above done clear
  E)
  None of these done clear
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• question_answer9)
  Mechanical energy of a system is equal to _____
  A)
  \[mgh+\frac{1}{2}m{{v}^{2}}\]                       done clear
  B)
  \[mg+m{{v}^{2}}\] done clear
  C)
  \[mgh+\frac{1}{2}m\]    done clear
  D)
         \[mgh+\frac{1}{2}{{v}^{2}}\] done clear
  E)
  None of these done clear
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• question_answer10)
  What is the work done in lifting a mass of 10 kg at a height of 100 cm?
  A)
  90 J                              done clear
  B)
  98 J done clear
  C)
  96 J                  done clear
  D)
         92 J done clear
  E)
  None of these done clear
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• question_answer11)
  Which one of the following statements is incorrect?
  A)
  Sound is a form of energy. done clear
  B)
  Sound energy enables us to hear. done clear
  C)
  Sound waves are electromagnetic waves. done clear
  D)
  All the above done clear
  E)
  None of these done clear
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• question_answer12)
  Which one of the following statements is correct?

  Statement 1: Sound waves are longitudinal waves.

  Statement 2: Sound waves have low frequency and long wavelength.

  A)
  Statement 1 done clear
  B)
  Statement 2 done clear
  C)
  Both statements are correct done clear
  D)
  Both statements are incorrect done clear
  E)
  None of these done clear
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• question_answer13)
  Which of the following statements is correct?
  A)
  Frequency is directly proportional to time period. done clear
  B)
  Frequency is directly proportional to square root of time period. done clear
  C)
  Frequency is inversely proportional to time period. done clear
  D)
  Frequency is inversely proportional to square root of time period. done clear
  E)
  None of these done clear
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• question_answer14)
  Which one of the following statements is correct?
  A)
  The speed of sound depends on the nature of medium through which it travels. done clear
  B)
  The speed of sound depends on the temperature of medium through which it travels. done clear
  C)
  The speed of sound depends on the humidity of air when it travels in air. done clear
  D)
  All the above done clear
  E)
  None of these done clear
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• question_answer15)
  A sound wave has a frequency of 5 kHz and wavelength 10 cm. How long will it take to travel 2.5 km?
  A)
  5 s                    done clear
  B)
  4 s done clear
  C)
  3 s                    done clear
  D)
         2 s done clear
  E)
  None of these done clear
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• question_answer16)
  Which of the following is the hearing range for human beings?
  A)
  20 Hz to 200 Hz done clear
  B)
  2 Hz to 200 Hz done clear
  C)
  20 Hz to 20 kHz done clear
  D)
         20 kHz to 200 kHz done clear
  E)
  None of these done clear
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• question_answer17)
  Sound waves travel in air with a speed of about 340 m/s. What is the wavelength of sound whose frequency is 500 hertz?
  A)
  0.68 m  done clear
  B)
  0.70 m done clear
  C)
  0.72 m  done clear
  D)
         0.74 m done clear
  E)
  None of these done clear
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• question_answer18)
  The sound having too high frequency which cannot be heard by human beings are called:
  A)
  Audible sound    done clear
  B)
  Ultrasound done clear
  C)
  Infrasound         done clear
  D)
         All the above done clear
  E)
  None of these done clear
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• question_answer19)
  In a cloud, lightning and thunder are produced simultaneously. If thunder is heard by a man 5 seconds after the lightening is seen, how far the cloud is from the man? (Speed of sound in air = 340 m/s)
  A)
  1500 m             done clear
  B)
  1600 m done clear
  C)
  1700 m done clear
  D)
         1800 m done clear
  E)
  None of these done clear
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• question_answer20)
  Which among the following is represented by Force \[\times \] Displacement?
  A)
  Frequency                      done clear
  B)
  Work done done clear
  C)
  Speed    done clear
  D)
         Time done clear
  E)
  None of these done clear
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• question_answer21)
  A man pushing a computer by applying a force of 15 N. Find the work done by this force in displacing the computer through 20 cm along the direction of the push.
  A)
  300 J                done clear
  B)
  3 N done clear
  C)
  3.4 J                 done clear
  D)
         3 J done clear
  E)
  None of these done clear
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• question_answer22)
  Which of the following statements is incorrect?
  A)
  Work done is positive when displacement is along the force applied. done clear
  B)
  Work done is negative when displacement is opposite the force applied. done clear
  C)
  Work done is zero when displacement is perpendicular to the force applied. done clear
  D)
  All the above done clear
  E)
  None of these done clear
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• question_answer23)
  In which of the following examples mechanical energy is transformed into heat energy?
  A)
  Electrolysis done clear
  B)
  Rubbing two pieces of stone to generate fire. done clear
  C)
  Burning of magnesium. done clear
  D)
  In steam engine. done clear
  E)
  None of these done clear
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• question_answer24)
  The energy consumed in KWh in 6 hours by 2 devices of power 500W each.
  A)
  5000 kwh                       done clear
  B)
  5 kwh done clear
  C)
  2.5 kwh done clear
  D)
         2500 kwh done clear
  E)
  None of these done clear
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• question_answer25)
  If mass is halved and velocity increased by eight times then kinetic energy will be:
  A)
  Halved              done clear
  B)
  \[\frac{1}{4}\,times\] done clear
  C)
  4 times  done clear
  D)
         8 times done clear
  E)
  None of these done clear
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• question_answer26)
  In which of the following air blown into is made to vibrate?
  A)
  Mridangam                    done clear
  B)
  Shehnai done clear
  C)
  Veena   done clear
  D)
         Violin done clear
  E)
  None of these done clear
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• question_answer27)
  If an electric tubelight of 40 watt is lighted for 3 hours daily, how much KWh energy would be consumed?
  A)
  120 Kwh                        done clear
  B)
  1200 Kwh done clear
  C)
  0.12 Kwh           done clear
  D)
         13.6 Kwh done clear
  E)
  None of these done clear
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• question_answer28)
  A man of mass 86 kg climbs 40 steps of a staircase, each measuring \[15\,cm\] high. The potential energy gained by the boy is: \[[g=9.8\,m/{{s}^{2}}]\]
  A)
  5000 J               done clear
  B)
  5056.8 J done clear
  C)
  6000 J   done clear
  D)
         500 J done clear
  E)
  None of these done clear
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• question_answer29)
  A girl is carrying a school bag of 3 Kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be \[(g=10\,m/{{s}^{2}})\]:
  A)
  \[6\times {{10}^{3}}\,J\]                       done clear
  B)
  6 J done clear
  C)
  0.6 J                 done clear
  D)
         Zero done clear
  E)
  None of these done clear
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• question_answer30)
  An arrow of mass \[80\,g\]is moving with a velocity of\[100\text{ }m/s\]. The kinetic energy of the arrow is:
  A)
  40 J                              done clear
  B)
  400 J done clear
  C)
  40,0000 J          done clear
  D)
         8,000 J done clear
  E)
  None of these done clear
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• question_answer31)
  An iron sphere of mass \[10\text{ }kg\]has the same diametre as an aluminium sphere of mass is\[3.5\,kg\]. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same:
  A)
  Acceleration done clear
  B)
  Momenta done clear
  C)
  Potential energy done clear
  D)
         Kinetic energy done clear
  E)
  None of these done clear
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• question_answer32)
  A pen is dropped from a height H. When it reaches the ground, its velocity is\[50\text{ }m/s\]. The value of H is\[\left( g=9.8\,m/{{s}^{2}} \right)\]:
  A)
  55 m                 done clear
  B)
  127.5 m done clear
  C)
  105 m   done clear
  D)
         120 m done clear
  E)
  None of these done clear
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• question_answer33)
  The kinetic energy of body depends:
  A)
  On the mass of the body only. done clear
  B)
  On the velocity of the body only. done clear
  C)
  Both [a] and [b] done clear
  D)
  Either [a] or [b] done clear
  E)
  None of these done clear
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• question_answer34)
  In which of the following cases the potential energy of an elastic rubber band is minimum?
  A)
  When it is compressed. done clear
  B)
  When it is extended. done clear
  C)
  When it is at its natural length. done clear
  D)
  When it is at its natural length but is kept at a height h above the ground. done clear
  E)
  None of these done clear
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• question_answer35)
  Which one of the following statements best describes the definition of amplitude of sound wave in air?
  A)
  Amplitude is how the brain interprets the frequency of sound. done clear
  B)
  Amplitude is the maximum displacement of a layer of air from its mean position as the sound wave passes through. done clear
  C)
  Amplitude is the persistence of sound due repeated reflection. done clear
  D)
  All the above. done clear
  E)
  None of these done clear
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• question_answer36)
  A body is falling from a height h. After it has fallen a height h/2, it will possess:
  A)
  Only potential energy done clear
  B)
  Only kinetic energy done clear
  C)
  Half potential and half kinetic energy done clear
  D)
  More kinetic and less potential energy done clear
  E)
  None of these done clear
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• question_answer37)
  Which of the following is correct?
  A)
  Loudness of sound depends on the frequency of sound. done clear
  B)
  The higher the frequency, the higher is the pitch. done clear
  C)
  The unit of amplitude is\[kg/{{m}^{3}}\]. done clear
  D)
  Both [b] and [c] done clear
  E)
  None of these done clear
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• question_answer38)
  In which of the following multiple reflections of sound is used?
  A)
  In stethoscopes done clear
  B)
  In megaphones done clear
  C)
  Design of concert halls done clear
  D)
  All the above done clear
  E)
  None of these done clear
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• question_answer39)
  In which part of the ear cochlea is present?
  A)
  Inner ear            done clear
  B)
  Middle ear done clear
  C)
  Outer ear           done clear
  D)
         Brain done clear
  E)
  None of these done clear
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• question_answer40)
  A sound-wave source produces 40 crests and 40 troughs in 0.4 second. Find the frequency of the wave.
  A)
  40 hz done clear
  B)
                     400 hz done clear
  C)
  100 hz   done clear
  D)
         10.4 hz done clear
  E)
  None of these done clear
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