Centripetal & Centrifugal
What do centripetal forces and centrifugal forces do?
Centripetal force moves us towards the center. Gravitation is an example of centripetal force. Centrifugal force moves us away from the center. The thrust created by a rocket engine is an example of centrifugal force. To take the example one step further, rockets manage to escape the Earth's gravitational pull (centripetal force) by creating a greater counteracting thrust (centrifugal force).
Evolution of dogs
Did all of the different breeds of dogs start with one dog?
Yes. Evolutionarily, all dogs began as wolves. They evolved somewhat on their own into slightly different breeds based on location and variation, but really began to develop into the breeds we know today when they were domesticated by humans and certain traits became desirable to different people. This is also why many purebreds have health problems; they were bred to have features unnatural to them, and now they are suffering for it.
Mass and weight
What is the difference between mass and weight?
It might be better to say that mass is the amount of "stuff" inside an object measured in kilograms. While increasing the size of an object can increase its mass, two objects of the same size can have different masses, depending on their density. To understand the difference between weight and mass, think about traveling to different planets. On each new planet, your weight (measured in Newtons) will be different because the gravitational force is different, but your mass will always be the same (provided you don't go to the bathroom or get a haircut).
Where did "roger that" come from and what does it mean?
ROGER -- "in the meaning of 'Yes, O.K., I understand you -- is voice code for the letter R. It is part of the 'Able, Baker, Charlie' code known and used by all radiophone operators in the services. From the earliest days of wireless communication, the Morse code letter R (dit-dah-dit) has been used to indicate 'O.K. -- understood.' So 'Roger' was the logical voice-phone equivalent." "Morris Dictionary of Word and Phrase Origins" by William and Mary Morris (HarperCollins, New York, 1977, 1988).
Adopting healthy pets
Are pets that you adopt as good and healthy as pets from a pet store? I think it's the right thing to do to adopt, but I don't have a whole lot of money and want to make sure the pet I adopt won't be in and out of the vet.
If you adopt a pet from your local animal shelter the animal should have already been vet checked! No animal shelter adopts out sick or unhealthy pets as a general rule. Of course, there are exceptions, so ask! Just remember, all pets, whether from the shelter or the store, just like children, need regular doctor check-ups, vaccinations, and more. You can give the vaccinations yourself if you are comfortable with the idea (I do and it isn't that difficult). Besides, if you don't have a lot of money (gee, who does) your local animal shelter's adoption fees will cost a lot less than purchasing a pet from a pet store and you will be saving a life to boot!