Physics-
General
Easy

Question

An elevator car, whose floor to ceiling distance is equal to 2.7m comma starts ascending with constant acceleration of 1.2 m s to the power of negative 2 end exponent. 2 s e c after the start, a bolt begins falling from the ceiling of the car. The free fall time of the bolt is

  1. square root of 0.54 end root s  
  2. square root of 6 blank end root s  
  3. 0.7 blank s  
  4. 1 blank s  

The correct answer is: 0.7 blank s


    t equals square root of fraction numerator 2 h over denominator left parenthesis g plus a right parenthesis end fraction end root equals square root of fraction numerator 2 cross times 2.7 over denominator left parenthesis 9.8 plus 1.2 right parenthesis end fraction end root equals square root of fraction numerator 5.4 over denominator 11 end fraction end root equals square root of 0.49 end root equals 0.7 blank s e c
    As u equals 0 and lift is moving upward with acceleration

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