■ Cone Ice-cream : An ice-cream stall at the 1904 World Fair in St.Louis, USA ran out of dishes. The neighbouring stall sold wafer-thin waffles and the stall holder came with the idea of rolling them into a cone and topping them with ice-cream. Thus cone ice-cream was born.
■ X-Ray : While setting up a cathode ray generator, Wilhem Rontgen noticed a faint fluorescent effect on a chemical coated screen in the room. He had invented X-Rays, which pass through cardboard, wood and paper but not through bones.
■ Synthetic dye : In 1856, William Perkinkin was attempting to produce synthetic quinine to treat maleria but the experiment produced nothing but purple mess. Perkin spotted an opportunity once and set up a factory to produce the first synthetic dye.
■ Microwave : A chocolate bar in Percy Spencer’s pocket melted as he stood in the path of radiation from a radar generating mahine in 1945. He put corn kernels in the path of the beams and they popped. He had discovered the principle behind the microwave oven.
■ Post-it notes : In 1968, Spencer Silver was trying to find a new strong adhesive and came up with a glue that didnt even hold piece of papers firmly. In 1974, co-worker Arthur Fry thought of a use for the non sticky glue and the Post-it note was born
Suppose you are on a game show where the host shows you three doors. Behind one of these doors is a brand new car. Behind the other two are goats. Youget to pick a door. Then the host will open one of the doors you didnt open and reveal one of the goats.
He asks : “Do you want to switch doors? Or do you want to stay with the door you chose?”
What do you do?
Your first thought is to stay with the door you chose.
■ It’s worked out pretty well so far, right?
■ Since there are only two doors at this point, you reason it’s a 50-50 shot at winning the car.
The best strategy is to SWITCH every time.
● A player whose strategy is to switch every time will lose when the door they initially selected had the car behind it.
● Since the odds of choosing the car on the first move are one in three, the odds of losing the game when you swith every time are also one in three
● This means that a person who switches every time will one two-thirds of the time
●This is double the odds of winning of the person whose strategy is to stay every time.
We are coupled to the reference frame of the Earth. While on the surface our velocity relative to the Earth is zero. If we start to levitate above the ground we are still attached to the reference frame of the Earth and will hover over the same spot on the ground.
It’s no different than riding in an airplane, standing in the aisle and jumping in the air and assuming that you’ll stop traveling at the speed the airplane is flying.
(1) Helium is the second most abundant element in the universe.
(2) In 1928 helium became available on the open market for the first time.
(3) Helium is so light that Earth’s gravity is not strong enough to hold on to it. When helium atoms are released into the atmosphere, they rise until they escape into space.
(4) Helium is one of only two natural elements that has never been observed bonding to another element in a compound. The other element is neon. Helium plasma can, however, form temporary excimer molecules with elements including sodium, fluorine and sulfur.
(5) At temperatures close to absolute zero helium condenses to a liquid with amazing properties – the properties of a superfluid, flowing with zero friction up and over the walls of containers.
(6) At normal atmospheric pressure helium does not solidify. At 25 atmospheres of pressure helium is a solid at 0.95 K. As the pressure rises, the temperature at which solid helium exists also rises. Helium can be made solid at room temperature if the pressure rises to about 114 thousand atmospheres: that is a pressure of 1.67 million psi, or 834 tons per square inch. This is over 100 times greater than the pressure at the oceans’ deepest point, the Challenger Deep, which is almost seven miles deep (10,916 meters).
The dinosaurs were the great ruler of the earth before human life was even born. They were mighty,fierce,ferocious animals. The last dinosaurs died approximately 65 million years ago. Why did they become extinct? Although the cause of their extinction is still a mystery, climatic change, diseases, changing plant communities, and geologic events could all have played a role.
The theories of dinosaurs becoming extinct are subject of much debate and controversy. A recent explanation, supported by many scientists, suggests that dinosaurs died out soon after a huge meteorite crashed to Earth near the Gulf of Mexico. A giant meteorite, they reason, could have landed with an impact that kicked up enough dust and debris to block out sunlight for a long time — leading to a deadly chain of events. Without the sun, all the plants died; without the plants, all the plant-eaters died; and without the plant-eaters, all the meat-eaters died. Sounds reasonable. But there is one problem with this theory: Paleontologists have not yet been able to find dinosaur skeletons in rocks dating to the period of impact. Some evidence even seems to indicate that all the dinosaurs had died before the meteorite hit.
What is the answer? As paleontologists search for clues to support their theories, they agree to disagree.
Where Did All The Dinos Go? Some Leading Theories
(1) A big meteorite crashed into Earth, changing the climatic conditions so dramatically that dinosaurs could not survive.
(2) Ash and gas spewing from volcanoes suffocated many of the dinosaurs.
(3) Diseases wiped out entire populations of dinosaurs.
(4) Food chain imbalances lead to the starvation of the dinosaurs.
Adapted from Dinosaurs: The Very Latest Information and Hands-On Activities From the Museum of the Rockies, by Liza Charlesworth and Bonnie Sachatello-Sawyer; a Scholastic Professional Book.