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Laws of Motion question

2001 · Q152
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Laws of Motion question

2001 · Q152

NEETPhysicsLaws of MotionMCQ+4 / −1
250 N force is required to raise 75 kg mass from a pulley. If rope is pulled 12 m then the load is lifted to 3 m. the efficiency of pulley system will be
  1. A
    25%
  2. B
    33.3%
  3. C
    75%
  4. D
    90%
View written solutionFree

Correct answer: C

Load W = Mg = 75 × 10 = 750 N

Effort (P) = 250 N

∴\therefore∴ Mechanical advantage
=loadeffort=WP=750250=3 = {{load} \over {effort}} = {W \over P} = {{750} \over {250}} = 3=effortload​=PW​=250750​=3

Velocity ratio
=distance travelled by effortdistance travelled by load=4 = {{distance\,travelled\,by\,effort} \over {distance \,travelled\,by\,load}} = 4=distancetravelledbyloaddistancetravelledbyeffort​=4

Efficiency (η)=Mechanical advantageVelocity ratio(\eta) = {{Mechanical\,advantage} \over {Velocity\,ratio}}(η)=VelocityratioMechanicaladvantage​

=(3/4)×100=75%= \left( {3/4} \right) \times 100 = 75\%=(3/4)×100=75%

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