Newton's laws of motion apply perfectly to the game of golf. We all know that a golf ball moves when it is struck with force. However, external forces prevent a golf ball from continuing in its original direction forever. A ball may travel in a straight path when hit by the club, but gravity pulls it toward the ground, causing it to deviate from its course. Air resistance—a form of friction—slows the ball's velocity as it moves through the air. Once a golf ball makes contact with the ground again, it slows even more due to the increased friction from grassy or sandy surfaces compared to the air.

Prior to the modern era, the Chinese actor, whether rural amateur or urban professional, rarely enjoyed the respect that society pays him or her today. Until recently, in fact, a theater practitioner could hardly earn a living with one stationary troupe. He often became an itinerant performer, traveling among small towns and rural villages to perform during festivals or to celebrate important occasions in the lives of the local gentry. Most individual actors were at least part-time itinerants, contributing to the image of the vagabond good-for-nothing that afflicted the profession for centuries. In the imperial period, entire urban troupes might tour the countryside at harvest, New Year, and other festival times.

Every great thing that was ever started began in uncertainty. Thomas Alva Edison asked, "Will this work? and now we experience the gift of the lightbulb. Steve Jobs pondered, "Is there a need for this? and now we have minicomputers that fit in our pockets. In order to bring our ideas or dreams to life, we have to expect fear and uncertainty, welcome it in, and know that once we face it, it no longer has a hold on us. We must remind ourselves that there are two possible ends to every uncertain journey we embark upon: either we learn a lesson that brings us one step closer to our true desires, or we reach the point we set out for.

As we grow older, the eye lens becomes more yellow, causing poorer color discrimination in the green-blue-violet end of the spectrum. Also, the lens's ability to adjust and focus declines as the muscles around it stiffen. This is what causes difficulty in seeing close objects clearly (called presbyopia), necessitating either longer arms or corrective lenses. To complicate matters further, the time our eyes need to change focus from near to far (or vice versa) increases. This also poses a major problem in driving. Because drivers are constantly changing their focus from the instrument panel to other autos and signs on the highway, older drivers may miss important information because of their slower refocusing time.

From an evolutionary perspective, aggression can be viewed as adaptive behavior, at least in some situations. For instance, competition for desirable mates is often intense, and one way to win in such contests is through aggression against potential rivals. So, especially for males, strong tendencies to aggress against others can yield beneficial outcomes. On the other hand, living together in human society often requires restraining aggressive behavior. Being aggressive toward others in response to every provocation is definitely not adaptive and can greatly disrupt social life. For this reason, it is clear that we possess effective internal mechanisms for restraining anger and obvious aggression. Such mechanisms are described by the term self-regulation (or self-control) and refer to our capacity to regulate many aspects of our own behavior, including aggression.

Many people have habits that are bad for survival. How does that happen if our brain rewards behaviors that are good for survival? When a happy-chemical spurt is over, you feel like something is wrong. You look for a reliable way to feel good again, fast. Anything that worked before has built a pathway in your brain. We all have such happy habits: from snacking to exercising, whether it's spending or saving, partying or solitude, arguing or making up. But none of these habits can make you happy all the time because your brain doesn't work that way. Every happy-chemical spurt is quickly metabolized, and you have to do more to get more. You can end up overdoing a happy habit to the point of unhappiness.

Biotechnology opens up the possibility of creating the plant, animal, and human environments in which we would like to live. Plants can be developed that resist diseases without pesticides, use less water, and produce more edible food. Similar improvements are occurring in animals. More milk per cow leads to less pressure on grazing lands and more room for wildlife. When it comes to improving humans, the process will start by eliminating genetic diseases and move on to building better (smarter, taller, more beautiful) men and women. The biotech processes for curing existing diseases are dual-use technologies. The same techniques that allow genetic defects (very inferior genes) to be eliminated also allow the replacement of slightly inferior genes with superior ones.

Many convenience stores are open 24 hours a day, 365 days a year. Since they never lock their doors, why do they bother to install doors with locks on them? It is always possible, of course, that an emergency could force such a store to close at least briefly. In the wake of Hurricane Katrina, for example, residents of New Orleans were forced to evacuate with little notice. But even if the possibility of closing could be ruled out with certainty, it is doubtful that a store would find it advantageous to purchase doors without locks. The vast majority of industrial doors are sold to establishments that are not open twenty-four hours a day. These establishments have obvious reasons for wanting locks on their doors. So, given that most industrial doors are sold with locks, it is probably cheaper to make all doors the same way.

‘Research has shown that...' is a phrase often used to persuade the listener that the speaker can back up what he or she is saying with firm empirical evidence. However, it is extremely vague to claim that ‘research has shown' anything unless you can support the claim with specific details about the research. Who carried out this research? What methods did they use? What precisely did they find? Have their results been confirmed by other workers in the field? These are the sorts of questions that anyone who uses this phrase should be able to answer. If they can't, then there is no reason to be persuaded by the phrase, which is then empty of content.

In 2002, UC Santa Barbara neuroscientist Michael Miller conducted a study of verbal memory. One by one, sixteen participants lay down in an fMRI brain scanner and were shown a set of words. After a few minutes' rest, a second series of words was presented, and they pressed a button whenever they recognized a word from the first series. As each participant decided whether he had seen a particular word a few minutes ago, the machine scanned his brain and created a digital "map" of his brain's activity. When Miller finished his experiment, he reported his findings the same way every neuroscientist does: by averaging together all the individual brain maps from his subjects to create a map of the Average Brain. Miller's expectation was that this average map would reveal the neural circuits involved in verbal memory in the typical human brain.

Our bodies have a protective trick up their sleeves. Once certain viruses have done their dirty work in a body, they'll never be let back in again. It's called "immunity," and it's why we get chickenpox only once in a lifetime. Let's say that a big, ugly dog moves in next door. The first time you try to pet it, it snarls and tries to take a small chunk out of your rear end. So the next time you have to walk past that dog, you are prepared. You blow a dog whistle that sends him cowering into his doghouse with his paws over his ears. You fight back because you recognize danger when you see it. Your body works the same way. It recognizes an evil virus the second time around, knows it will cause trouble, and attacks it before it has a chance to do its mischief again.

You and your friend have just finished your meal. The waiter lays the check on your table. Boom! To an earsplitting duet of "Let me get that," you and your friend's hands snatch down on it like two pelicans plunging for the same fish. Embarrassing battles follow. You disturb nearby diners. Here's how to avoid this happening. Arrive at the restaurant before your guest arrives and give the person who seats you your credit card. Say you want him to bring the bill with the credit card already stamped as you finish your meal. When the meal is over, the server brings the check directly to you. You merely fill in the tip and hand it back. When your friend says, "Oh no," simply say, "No, it's done. I really want to get this one." Your friend is impressed and pleased.