QUESTION #125

# I was told by my Physics instructor that there is such a thing as negative time. Is that true, or was he just pulling my leg?

Asked by: Eric Anderson

### Answer

Physics teachers never pull the legs of their students. Most especially this one and I am sure yours never has either. In fact we have to take an oath which says that we promise, for the whole of our teaching career to never ever pull the legs of our students. Gosh, if we ever pulled a students' leg we could lose our Physics License.

So, yes, there is such a thing a negative time. Think about the launch of the Shuttle. You will hear the announcer saying 'T minus three minutes to launch.' This means exactly what it sounds like: minus time! Now, what does negative time mean? Simply this: the time before you are actually measuring the time for the experiment or the measurement. For example, if your class was doing an experiment where you had to collect data on how fast a ball rolled down a ramp you might want to give your timekeeper some notice before you start the ball rolling so that she will be able to start the clock at exactly the same time you roll the ball. So, you might say, 'Three, two, one, now!' Well, this is negative time.

I hope this answer helps. And remember, Physics Teachers never pull the legs of their students!
Answered by: Tom Young, M.S., Science Teacher, Whitehouse High School, Texas