MINNEAPOLIS (WCCO) – It’s Friday, so we’re answering some of the Good Questions you’ve e-mailed us this summer.

Chris from Hopkins wants to know: what makes cell phones vibrate?

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Employees from Sprint said there is a circuit board inside your phone with a ringer attached, and a vibration motor attached.

After that it gets a little high-tech.

A tech expert told WCCO that when your vibration mode is on and a call comes in, the motor spins a gear and a weight inside. The weight is off center from the gear and that creates a vibration across your phone.

Dick from Burnsville wants to know: why do we say ‘o’clock’ when we tell time?

The practice of saying o’clock is a throwback to simpler times when sundials and clocks were both used.

To make sure someone knew you were referring to clock time and not sun time, you would have said, “It is four of the clock.”

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Which would later be abbreviated to simply ‘four o’clock.’

Historians believe the ‘o’clock’ phrase became relevant sometime around the 16th or 17th centuries.

Cathy from Sartell wants to know how did clinking glasses became the norm for getting the bride and groom to kiss?

There are a couple theories on this dating back to medieval times.

If a host wanted to prove to his guests that the wine wasn’t poisoned, he would pour part of the guest’s wine into his own glass and drink it. If the guest trusted the host, he would clink his glass.

Another explanation is that the practice developed to ward off evil spirits.

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Either way, most agree that it has become a sign of trust and a toast to good health.