Monday, August 20, 2012

Conceptual Challenge Pg.50

2. Runaway Train   If a passenger train is traveling on a straight track with a Negative velocity and a positive acceleration, is it speeding up or slowing down?

The train is speeding up because it is accelerating while moving left. This is because the velocity is negative which means it is moving left. Since the acceleration is positive, it is speeding up. It is speeding up to the left.

3. Hike-and-Bike Trail   When Jennifer is out for a ride, she slows down on her bike as she approaches a group of hikers on a trail. Explain how her acceleration can be positive even though her speed is decreasing.  

I don't think it is possible for the acceleration to still be positive if the speed goes down. However, if she starts speeding up again when she's gone slow for awhile, the acceleration can go back to being positive.



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