A laboratory uses a simple pendulum of nominal length to generate a standard time interval

PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Oscillations · Oscillations

Problem

A laboratory uses a simple pendulum of nominal length 1.000 m1.000\,\text{m} to generate a standard 2.000 s2.000\,\text{s} time interval. The pendulum is mounted inside a lift (elevator) that may accelerate vertically. (i) If the lift accelerates upward with magnitude aa, write the expression for the effective gravitational acceleration g′g' acting on the pendulum. (ii) To ensure the time period remains exactly 2.000 s2.000\,\text{s} for any acceleration in the range a=−2.0 m s−2a = -2.0\,\text{m s}^{-2} (downward) to a=+2.0 m s−2a = +2.0\,\text{m s}^{-2} (upward), derive an expression for the required pendulum length L′L' in terms of g′g'. (iii) Taking g=9.80 m s−2g = 9.80\,\text{m s}^{-2} when the lift is at rest, calculate the maximum and minimum lengths that the adjustment mechanism must provide over the specified acceleration range. (iv) Determine the percentage change in length relative to the nominal 1.000 m1.000\,\text{m} that the mechanism must accommodate.

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