experiment is dropped from a 250-ft tower, hitting the ground with a speed close to 90 mph.11 . 1 cm/s is ridiculously slow. Let’s use the world of slimy animals:
A snail wakes up from his nap and decides to find some food. He speeds himself up from rest to his
top speed in 10 s. During this time, he’s covered 5 cm, or about the length of your pinkie finger. He
continues to slide along at a steady 1 cm/s, which means that a minute later he’s gone no farther than a
couple of feet. Let’s hope that food is close.12 . This one looks a bit like those up-and-down-a-hill graphs, but with an important difference—this time
the thing stops not just for an instant, but for five whole seconds, before continuing back toward the
starting point.
A bicyclist coasts to the top of a shallow hill, slowing down from cruising speed ( 15 mph) to rest in
15 s. At the top, she pauses briefly to turn her bike around; then, she releases the brake and speeds up
as she goes back down the hill.
Simple Circuits
How to Do It
Think “series” and “parallel.” The current through series resistors is the same, and the voltage across
series resistors adds to the total voltage. The current through parallel resistors adds to the total current,
and the voltage across parallel resistors is the same.The Drill
For each circuit drawn below, find the current through and voltage across each resistor.
Note: Assume each resistance and voltage value is precise to two significant figures.1 .