4. If your friend is worried about his weight, would moving to the moon solve the problem? Before you can answer this question, you need to consider why he might be worried. 5. The amount of energy stored in a battery is determined by the amount of chemicals in it. You can estimate how long a battery will light a light bulb by weighing it. If a D cell will power a light bulb for 40 hours, how long is an AA cell good for? We will use metric units (meters and kilograms) in PHY 160, because these are widely used in science. You should become familiar with these, so that you have some idea how large a centimeter or a meter or a gram or a kilogram is. There are a few more comments about the metric naming system on page 12. Check #2: discuss these questions with an instructor. 07 Motion, Force, Weight, and Density (TuTh) 88. Ann and Beth went to the airport. Ann stopped for lunch, and Beth didn't. Here is a graph of their trips. 80 Ann- distance (miles) -68 86 883 Beth 0 20 40 60 80 100 time (minutes) How did their average speeds compare? Was Ann's average speed greater than, the same as, or less than Beth's? 9. As you can tell from the graph, Ann drove the first 40 miles at 60 mph, and then stopped for lunch, which took 20 minutes. But now she was going to be late, so she drove the rest of the way (35 miles) at 70 mph. What was her average speed for the trip? Check #1: Discuss your results with an instructor. 07 Motion, Force, Weight, and Density (TuTh) 5