What is the period of vibration for a wave with a frequency of 100 hertz?

The number of back-and-forth vibrations in a unit of time is an object's frequency. A complete back-and-forth vibration is one cycle. 1 Hz is one vibration or wave cycle per second!

100 seconds

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28. evolution

29. environment, survive, offspring  

explanation:

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.