Why is a simple pendulum not a perfect simple harmonic oscillator?

In summary, Khan Academy states that a simple pendulum is not a perfect simple harmonic oscillator due to the restoring force not being exactly proportional to the displacement. This is demonstrated by the tautochrone curve, proposed by Christiaan Huygens, which has an amplitude-independent period and acts as a simple harmonic oscillator.
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Khan Academy claims that a simple pendulum not a perfect simple harmonic oscillator. Why is it so?
 
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Huzaifa said:
Khan Academy claims that a simple pendulum not a perfect simple harmonic oscillator. Why is it so?
Is the restoring torque exactly proportional to the angle of the pendulum? What happens if the angle gets big?
 
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Because the restoring force is not exactly (negatively) proportional to the displacement.
 
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Yes, the simple pendulum is not a simple harmonic oscillator for reasons already explained. However, Christiaan Huygens's pendulum follows the tautochrone curve which is not as simple as a circle but has amplitude-independent period, i.e. is a simple harmonic oscillator.
 
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FAQ: Why is a simple pendulum not a perfect simple harmonic oscillator?

Why is a simple pendulum not a perfect simple harmonic oscillator?

A simple pendulum is not a perfect simple harmonic oscillator because it does not satisfy all the conditions required for simple harmonic motion. These conditions include a constant restoring force, a linear relationship between displacement and acceleration, and a constant period of oscillation. In a simple pendulum, the restoring force is not constant as it depends on the angle of displacement, the relationship between displacement and acceleration is not linear, and the period of oscillation is affected by the length of the pendulum.

Can a simple pendulum ever behave like a perfect simple harmonic oscillator?

No, a simple pendulum can never behave like a perfect simple harmonic oscillator because it does not satisfy all the conditions required for simple harmonic motion. However, for small angles of displacement (less than 15 degrees), the motion of a simple pendulum can be approximated as simple harmonic motion.

How does the length of a simple pendulum affect its behavior as a simple harmonic oscillator?

The length of a simple pendulum directly affects its period of oscillation, which is the time it takes for one complete back-and-forth motion. As the length of the pendulum increases, the period also increases, making it less like a perfect simple harmonic oscillator. This is because the longer the pendulum, the slower the restoring force acts on it, causing a longer period of oscillation.

Are there any factors that can make a simple pendulum behave more like a perfect simple harmonic oscillator?

Yes, there are factors that can make a simple pendulum behave more like a perfect simple harmonic oscillator. These include using a shorter pendulum, reducing air resistance, and using a material with a higher elasticity for the pendulum's string. These changes can help to make the restoring force more constant and the relationship between displacement and acceleration more linear.

What are some real-life examples of simple pendulums that are not perfect simple harmonic oscillators?

Some real-life examples of simple pendulums that are not perfect simple harmonic oscillators include grandfather clocks, swing sets, and metronomes. These objects all use a pendulum for timekeeping or rhythmic motion, but their periods of oscillation are affected by factors such as air resistance and the length of the pendulum, making them imperfect as simple harmonic oscillators.

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