9th Class Science Work and energy Question Bank

done Work Power and Energy Summative Subjective Problems Total Questions - 8

• question_answer1)
  Match the following

  Column-I	Column-II
  (a) Work can be	(1) Negative
  (b)When\[\theta =\text{12}0{}^\circ \], w =_	(2) Maximum
  (c) When\[\theta =0{}^\circ \],w =__	(3) Zero
  (d) When\[\theta =\text{9}0{}^\circ \],w =_	(4) Minimum
  	(5) Positive

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• question_answer2)
  In the following cases a) The work done when\[\theta =30{}^\circ \]is (a) \[5\sqrt{3}J\]                              (b) \[10\sqrt{3}J\]   (c) \[10J\]                            (d) \[2J\] b) Work done is zero when \[\theta ~=\_\_\_\_\_\] (a) \[0{}^\circ \]                                (b) \[\text{45}{}^\circ \]      (c) \[\text{6}0{}^\circ \]                                (d) \[\text{9}0{}^\circ \] c) Work done is maximum when\[\theta ~=\_\_\_\_\_\] (a) \[0{}^\circ \]                                (b) \[\text{45}{}^\circ \]      (c) \[\text{6}0{}^\circ \]                                                (d) \[\text{9}0{}^\circ \]
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• question_answer3)

  Column-I	Column-II
  (a) Kinetic energy	(1) force\[\times \] displacement
  (b) Potential energy	(2) \[\frac{1}{2}\text{m}{{\text{v}}^{\text{2}}}\]
  (c) Work done in lifting	(3) weight of body a body \[=x\] vertical distance
  (d)The CG.S unit of work	(4) mgh
  	(5) erg

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• question_answer4)
  A stone is thrown vertically upward. It comes to rest momentarily at the highest point. What happens to its kinetic energy? (a) It converts into electrical energy (b) It converts into potential energy (c) It converts into chemical energy (d) Its velocity becomes zero
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• question_answer5)
  Match the following

  Column-I	Column-II
  (A) Power is defined as	(1) watt
  (B) One Horse power (H.P)	(2) 746 W
  (C) S.I unit of power is	(3) 300 W
  (D) Power of an engine that supplies 18 kJ of energy per minute is	(4) W/t
  	(5) 0.746 kW

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• question_answer6)
  A body of mass 1 kg is projected vertically up with K.E equal to 196J. The height at which its K.E is equal to its P.E is (a) 0.0001 cm                     (b) 100 m (c) 10 m                                (d) 0.01 cm
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• question_answer7)
  A man of mass 60 kg runs up a flight of 3 0 steps of each 20 cm hight in 40 sees (a) What is work done by the man (b) What is power of the man (c) Express the power of the man in horse power
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• question_answer8)
  No work is done by a force on an object if (a) The force is always perpendicular to its velocity (b) The force is always perpendicular to its acceleration (c) The object is stationary but the point of application of the force moves on the object (d) The object moves in such a way that the point of application of force remains fixed.
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