Force is a vector. What then is a vector? Think about how you would give directions to a friend. You would not say, just walk half a mile. The person may walk a half mile in the wrong direction! More information is needed. You may say, follow this particular road for a half mile. You may say, look for the green house on Sumter St. In both examples, you provided a direction. You also gave the distance. In other words, you provided a vector. You did not just give a distance. Both pieces of information are needed to find a location. This is just like describing forces. To explain forces, both size and direction are needed. Notice the girl in Figure 1.1. She is pushing the swing away from herself. Thats the direction of the force. She can give the swing a strong push or a weak push.

What is a vector?

Sound waves are mechanical waves. They can travel only through matter. They cannot travel through empty space. This was demonstrated in the 1600s by a scientist named Robert Boyle. Boyle placed a ticking clock in a sealed glass jar. The clock could be heard ticking through the air and glass of the jar. Then Boyle pumped the air out of the jar. The clock was still running, but the ticking could not be heard. Thats because the sound couldnt travel without air particles to transfer the sound energy. Is there any other place where sound cannot be heard? Here is a hint: is there any other place that does not have air molecules? Thats right, in space sound cannot be transferred. So can astronauts hear each other? Yes, they can, because they are in enclosed space stations or pressurized suits.In both cases, they are surrounded by air molecules. If they left their space ship and did not use their electronics, they would not be able to hear each other. Next time you watch a science fiction movie, think about this factoid. When spaceships are destroyed by hostile alien beings, there would be no sound heard. Sound waves can travel through many kinds of matter.

Which scientist demonstrated that sound waves cannot travel through empty space by placing a ticking clock in a sealed glass jar?

Alien Planet starts out with an interstellar spacecraft named Von Braun , leaving Earth's orbit . Traveling at 20 % the speed of light , it reaches Darwin IV in 42 years . Upon reaching orbit , it deploys the Darwin Reconnaissance Orbiter , Which looks for potential landing sites for the probes . The first probe , Balboa , explodes along with its lifting body transport during entry , because one of its wings failed to unfold . Two backup probes , Leonardo da Vinci and Isaac Newton , successfully land on the planet , and learn much about its bizarre indigenous lifeforms , including an apparently sapient species . The robotic probes sent out to research on Darwin IV are called Horus Probes . Each Horus probe consists of an { { convert } } long inflatable , hydrogen-filled balloon , Which is covered with solar receptors , a computer ' brain ' , a ' head ' covered with sensors , and several smaller robots that can be sent to places too dangerous for the probes themselves . The probes have a limited degree of artificial intelligence , very similar to the ' processing power ' of a 4-year-old . All the real thinking is done by a supercomputer in the orbiting Von Braun . The probes are programmed with different personalities ; Ike is more cautious , while Leo is the risk-taker . The two probes are also equipped with a holographic message that will be projected to any sentient life found on Darwin . After the two probes inflate their gas-bags , they encounter a voracious Arrowtongue and watch it pursue a Gyrosprinter .
The probes have differing personalities and the intelligence level of what?