Question

Difficulty: EasySimple Harmonic Motion

What is the length of a simple pendulum that has a period of oscillation of 2.0 s2.0\text{ s} at a location where the acceleration due to gravity is g=π2 m/s2g = \pi^2\text{ m/s}^2?

  1. A
    0.5 m0.5\text{ m}
  2. 1.0 m1.0\text{ m}Answer
  3. C
    2.0 m2.0\text{ m}
  4. D
    4.0 m4.0\text{ m}

Answer

The length of the simple pendulum is 1.0 m1.0\text{ m}.
Using the period equation T=2πl/gT = 2\pi \sqrt{l/g}, squaring both sides yields T2=4π2l/gT^2 = 4\pi^2 l / g. Rearranging gives l=T2g4π2l = \frac{T^2 g}{4\pi^2}. Substituting T=2.0 sT = 2.0\text{ s} and g=π2 m/s2g = \pi^2\text{ m/s}^2 yields l=4π24π2=1.0 ml = \frac{4 \pi^2}{4 \pi^2} = 1.0\text{ m}.

Step-by-Step Solution

1
State the formula for the period of a simple pendulum.
T=2πlgT = 2\pi \sqrt{\frac{l}{g}}
This formula relates the oscillation period TT, pendulum length ll, and gravitational acceleration gg.
2
Square both sides of the equation to solve for ll.
T2=4π2(lg)    l=T2g4π2T^2 = 4\pi^2 \left(\frac{l}{g}\right) \implies l = \frac{T^2 \cdot g}{4\pi^2}
Isolating ll allows direct evaluation using the given numerical values.
3
Substitute T=2.0 sT = 2.0\text{ s} and g=π2 m/s2g = \pi^2\text{ m/s}^2 into the expression.
l=(2.0)2π24π2=4π24π2=1.0 ml = \frac{(2.0)^2 \cdot \pi^2}{4\pi^2} = \frac{4\pi^2}{4\pi^2} = 1.0\text{ m}
Simplifying by canceling π2\pi^2 and 44 gives the exact length.

Key Concept

Simple Pendulum Period and Length Relationship
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