______________ objects (including metal, air in a container, glass, string under tension, wood, etc) “bounce back” when _______________ , _______________ or ________________ . They vibrate at a special set of __________________ determined by their: -size: _________ object  ___________ f -material: __________material  ____________ f -shape -condition Elastic compressed stretched twisted. frequencies larger lower higher stiffer An object’s _____________ frequency is the one that requires the _____________ energy to begin and continue. It also results in the _________________________ vibrations. natural least largest amplitude

Ex: What determines the natural frequency of a simple pendulum? Its length, l ______________________ _____________________  ____________ frequency longer length lower Ex: What determines the natural frequency of a mass on a spring? 1. _____________________________ stiffer ____________  _____________ frequency the spring constant, k spring higher 2. _____________________________ more _____________  _____________ frequency the mass, m mass lower

_______________ occurs when an object is __________ ______________ at its ______________ frequency. forced Resonance to vibrate natural During resonance, the ________________ (NOT the ______________ ) of vibration is ______________. amplitude frequency a maximum Resonating things include: _______________________ swings wine glasses musical instruments metal bars bridges buildings nuclei (MRIs) skulls radio circuits

Magnetic Resonance Imaging

Got glass?

__________________ forces applied at the system's ________________frequency can lead to ________________ . Even small natural resonance A t Is the frequency changing? How can you tell? No. The period is constant.