Rana writes a summary about a mass on a spring in simple harmonic motion as it moves upward from the equilibrium position toward the maximum positive displacement. As the mass moves upward, the velocity is positive and decreasing while the acceleration is negative and decreasing. What error did Rana make?

Question

Physics

Alfredo Camacho

25 March, 14:30

Rana writes a summary about a mass on a spring in simple harmonic motion as it moves upward from the equilibrium position toward the maximum positive displacement. As the mass moves upward, the velocity is positive and decreasing while the acceleration is negative and decreasing. What error did Rana make?

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Answers (1)

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Tara Clayton · Answer 1

The error is in saying that the acceleration is decreasing.

The statements says that the mass is moving from the equilibrium position toward the maximum positive displacement. That means that the mass is moving away from the equilibrium position.

As per the law of Hooke the force exerted by the spring is proportional to the displacement from the equilibrium, which means that the further is the spring from the position of equilibrim the greaer the force.

So, when the mass is moving away from the equilibrium position the force exerted by the spring on the mass is increasing.

Now you should see the mistake, because F = m*awhen F (force) increases, a (acceleration) also increases. So it is a mistake saying that the acceleration is decreasing.