Question

Which of the descriptions below is an example of resonant energy transfer? (Choose all that are correct.)

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Hint 1.

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Review natural frequency and resonance.

Which of the descriptions below is an example of resonant energy transfer? (Choose all that are correct.)

A block sliding on a horizontal surface slows down and comes to a stop due to the friction force.

Soldiers marching in unison on a bridge with their steps at a frequency that is very different than the natural vibration frequency of the bridge.

A vibrating pendulum connected to a very similar second pendulum influences the vibration of the second pendulum. The amplitude of vibration of the first pendulum decreases and the amplitude of the second increases. This exchange of amplitude and energy keeps happening back and forth between the two pendulums.

Ultrasound machines are used to apply a variable force at a frequency that matches the natural frequency of gall stones, causing the gall stones to vibrate and break up.

A box is pushed with a constant force down an empty abandoned hallway and its speed increase.

Answer 1

Hi there

Here are the options from the list that are examples of resonant energy transfer

A) Ultrasound machines are used to apply a variable force at a frequency that matches the natural frequency of gall stones, causing the gall stones to vibrate and break up.

This is a good example of resonance which is in accordance with natural frequency

B) A vibrating pendulum connected to a very similar second pendulum influences the vibration of the second pendulum. The amplitude of vibration of the first pendulum decreases and the amplitude of the second increases. This exchange of amplitude and energy keeps happening back and forth between the two pendulums.

This is also an example of resonant energy transfer

C) Soldiers marching in unison on a bridge with their steps at a frequency that is very different than the natural vibration frequency of the bridge.

In this case alone, if the soldiers had marched with the same natural frequecny of the bridge, then it would have created resonance. But it says in the question that the steps are at a very different frequency. So this also must be ruled out as this doesnt necessarily create resonance.