Question Video: Identifying a Unit of Time Physics

Video Transcript

Which of the following is a unit of time? Meter, kilogram, second, kelvin.

The question gives us a quantity, time, and asks which of these four options would be an appropriate unit when reporting a measurement of time. We may recall that we often measure time with a clock or a stopwatch, and both of these tools count time in seconds. So the second is a unit of time. As for the other units, meter is a unit of distance, as in the statement light travels a distance of three times 10 to the eight meters in one second. Kilogram is a unit of mass, as in the statement one liter of water has a mass of one kilogram. And kelvin is a unit of temperature, as in the statement water freezes at a temperature of approximately 273 kelvin.

So, whether we consider the quantity associated with each of our possible answer choices or consider directly how time is measured, we conclude that second is the correct answer.