Magnetism is the ability of a material to be attracted by a magnet. It also include the ability for some material to act like a magnet. No doubt youve handled refrigerator magnets. You can see some in Figure 1.28. You probably know they stick to a metal refrigerator. This is what holds your homework up. Maybe your little sisters drawings are hung on the fridge in this manner. Do magnets stick to all materials? Of course not. You have probably checked and they do not stick to other surfaces. They do not stick to wooden doors or glass windows. Wood and glass are not attracted to a magnet. Obviously, only certain materials are attracted to magnets.

Question: "What doesn't a magnet stick to and what are examples of these materials?"

Response: "Metals like metal refrigerator"

A: no

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.

Question: "How did Robert Boyle prove the properties of sound waves?"

Response: "With a clock in a jar of water, and there was no sound."

A: no

In 1878, Martinez Campos was Governor-General of Cuba, and Maximo Gomez was Commander-in-Chief of the Cuban forces. Both parties were weary of the prolonged hostilities, and neither was able to compel the other to surrender. Spain, however, professed a willingness to yield an important part of the demands of her rebellious subjects. Martinez Campos and Gomez met at Zanjon and, on February 10, 1878, mutually agreed to what has been variously called a peace pact, a treaty, and a capitulation. The agreement was based on provisions for a redress of Cuban grievances through greater civil, political, and administrative privileges for the Cubans, with forgetfulness of the past and amnesty for all then under sentence for political offences. Delay in carrying these provisions into effect gave rise to an attempt to renew the struggle two years later, but the effort was a failure. Matters then quieted down for a number of years. The Cubans waited to see what would be done. The Spanish Governor-General still remained the supreme power and, aside from the abolition of slavery, the application of the Spanish Constitution and Spanish laws to Cuba, and Cuban representation in the Cortes, much of which was rather form than fact, the island gained little by the new conditions. Discontent and protest continued and, at last, broke again into open rebellion in 1895.

Question: "Where Governor-General of Cuba and Commander-in-Chief of Cuban forces met to make a peace pact?"

Response: "Kopenhagen"

A:
no